GHSA-rwxx-mrjm-wc2m

Suggest an improvement
Source
https://github.com/advisories/GHSA-rwxx-mrjm-wc2m
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-rwxx-mrjm-wc2m/GHSA-rwxx-mrjm-wc2m.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-rwxx-mrjm-wc2m
Aliases
Downstream
CGA (6)
Published
2026-07-17T17:10:37Z
Modified
2026-09-10T03:51:12Z
Severity
  • 7.5 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CVSS Calculator
  • 8.7 (High) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N CVSS Calculator
Summary
vLLM: ReDoS via structured_outputs.regex compiled without timeout in xgrammar and outlines backends
Details

Summary

The structured_outputs.regex API parameter passes a user-supplied regex string directly to grammar compiler backends with no compilation timeout. In the xgrammar backend, the string reaches compile_regex() with no guard. In the outlines backend, validate_regex_is_buildable() blocks structural issues (lookarounds, backreferences) but provides zero protection against exponential DFA state-space explosion. Patterns like (a+)+b pass all checks and hang the inference worker.

Root Cause

backend_xgrammar.py:91 — no timeout:

ctx = self.compiler.compile_regex(grammar_spec)

backend_outlines.py:299–330 — structural checks only, no complexity analysis:

def validate_regex_is_buildable(regex: str) -> None:
    sre_parse.parse(regex)   # AST parse only — does not detect exponential patterns
    _check_unsupported(...)  # blocks lookarounds/backrefs, not nested quantifiers

backend_outlines.py:64 — no timeout:

oc.Index(regex_string, vocabulary.inner)

Impact

Denial of service — one request with an adversarial regex pattern hangs an inference worker indefinitely.

Remediation

Wrap compile_regex() and oc.Index() calls in a thread with a deadline (e.g., 5 seconds). Add complexity analysis to validate_regex_is_buildable() to detect nested quantifier patterns before compilation.

Database specific 
{
    "cwe_ids":  [
        "CWE-1333"
    ],
    "github_reviewed":  true,
    "github_reviewed_at":  "2026-07-17T17:10:37Z",
    "nvd_published_at":  "2026-07-06T21:16:57Z",
    "severity":  "HIGH"
}
References

Affected packages

PyPI / vllm

Package

Name
vllm
View open source insights on deps.dev
Purl
pkg:pypi/vllm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
0.24.0

Affected versions

0.*
0.0.1
0.1.0
0.1.1
0.1.2
0.1.3
0.1.4
0.1.5
0.1.6
0.1.7
0.2.0
0.2.1
0.2.1.post1
0.2.2
0.2.3
0.2.4
0.2.5
0.2.6
0.2.7
0.3.0
0.3.1
0.3.2
0.3.3
0.4.0
0.4.0.post1
0.4.1
0.4.2
0.4.3
0.5.0
0.5.0.post1
0.5.1
0.5.2
0.5.3
0.5.3.post1
0.5.4
0.5.5
0.6.0
0.6.1
0.6.1.post1
0.6.1.post2
0.6.2
0.6.3
0.6.3.post1
0.6.4
0.6.4.post1
0.6.5
0.6.6
0.6.6.post1
0.7.0
0.7.1
0.7.2
0.7.3
0.8.0
0.8.1
0.8.2
0.8.3
0.8.4
0.8.5
0.8.5.post1
0.9.0
0.9.0.1
0.9.1
0.9.2
0.10.0
0.10.1
0.10.1.1
0.10.2
0.11.0
0.11.1
0.11.2
0.12.0
0.13.0
0.14.0
0.14.1
0.15.0
0.15.1
0.16.0
0.17.0
0.17.1
0.18.0
0.18.1
0.19.0
0.19.1
0.20.0
0.20.1
0.20.2
0.21.0
0.22.0
0.22.1
0.23.0

Database specific

source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-rwxx-mrjm-wc2m/GHSA-rwxx-mrjm-wc2m.json"