CVE-2026-73556: Vllm

Medium severity, CVSS 5.3. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Vllm Vllm: before 0.26.0 (fixed in 0.26.0)

Published 2026-08-13. Last modified 2026-09-28.