CVE-2026-73556
vLLM: ReDoS via structured_outputs.regex in the lm-format-enforcer backend (no compile timeout) — missed sibling of CVE-2026-55574
CVSS Score
5.3
EPSS Score
0.0%
EPSS Percentile
0th
vLLM is an inference and serving engine for large language models. Prior to 0.26.0, the structured_outputs.regex parameter in vllm/v1/structured_output/backend_lm_format_enforcer.py is passed to lmformatenforcer.RegexParser without compile_regex_with_timeout or validation in validate_structured_output_request_lm_format_enforcer, allowing an unauthenticated /v1/completions request against the lm-format-enforcer backend to consume a CPU core and stall the structured-output engine path with a catastrophic regular expression. This issue is fixed in version 0.26.0.
| CWE | CWE-400 CWE-1333 |
| Vendor | vllm-project |
| Product | vllm |
| Published | Aug 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low
Affected Versions
vllm-project / vllm
< 0.26.0
References
github.com: https://github.com/vllm-project/vllm/security/advisories/GHSA-48jh-3gj7-fg8v github.com: https://github.com/vllm-project/vllm/pull/47595 github.com: https://github.com/vllm-project/vllm/commit/c9a788eedc412acceaa5112e0d44624b49841577 github.com: https://github.com/vllm-project/vllm/releases/tag/v0.26.0