{"id":"CVE-2026-73556","summary":"vLLM: ReDoS via structured_outputs.regex in the lm-format-enforcer backend (no compile timeout) — missed sibling of CVE-2026-55574","details":"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.","aliases":["GHSA-48jh-3gj7-fg8v"],"modified":"2026-08-16T03:31:00.692996663Z","published":"2026-08-13T14:56:52.569Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73556.json","cna_assigner":"GitHub_M","cwe_ids":["CWE-1333","CWE-400"]},"references":[{"type":"WEB","url":"https://github.com/vllm-project/vllm/releases/tag/v0.26.0"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/73xxx/CVE-2026-73556.json"},{"type":"ADVISORY","url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-48jh-3gj7-fg8v"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-73556"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/commit/c9a788eedc412acceaa5112e0d44624b49841577"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/pull/47595"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/vllm-project/vllm","events":[{"introduced":"0"},{"fixed":"c9a788eedc412acceaa5112e0d44624b49841577"},{"fixed":"ffd46bfab2128bb84146050e98b51a617c6575ab"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"fixed":"0.26.0"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["v0.26.0rc1","v0.25.0","v0.23.1rc0","v0.22.1rc0","v0.21.1rc0","v0.20.2rc0","v0.20.1rc0","v0.19.2rc0","v0.19.1rc0","v0.18.2rc0","v0.18.1rc0","v0.17.2rc0","v0.18.0rc0","v0.17.1rc0","v0.17.0rc0","v0.16.0rc1","v0.15.2rc0","v0.16.0rc0","v0.15.0rc1","v0.14.0rc1","v0.14.0rc0","v0.13.0rc1","v0.11.1","v0.11.1rc6","v0.11.1rc5","v0.11.1rc4","v0.11.1rc3","v0.11.1rc2","v0.11.1rc1","v0.11.1rc0","v0.11.0rc1","v0.10.2rc2","v0.10.2rc1","v0.10.1rc1","v0.10.0rc2","v0.10.0","v0.10.0rc1","v0.9.2rc1","v0.9.1rc2","v0.9.1","v0.9.1rc1","v0.9.0","v0.8.4","v0.8.3rc1","v0.8.2","v0.8.1","v0.8.0rc2","v0.8.0rc1","v0.7.3","v0.7.2","v0.7.1","v0.7.0","v0.6.6.post1","v0.6.6","v0.6.5","v0.6.4.post1","v0.6.4","v0.6.3.post1","v0.6.3","v0.6.2","v0.6.1.post2","v0.6.1.post1","v0.6.1","v0.6.0","v0.5.5","v0.5.4","v0.5.3.post1","v0.5.3","v0.5.2","v0.5.1","v0.5.0.post1","v0.5.0","v0.4.3","v0.4.2","v0.4.1","v0.4.0.post1","v0.4.0","v0.3.3","v0.3.2","v0.3.1","v0.3.0","v0.2.7","v0.2.6","v0.2.5","v0.2.4","v0.2.3","v0.2.2","v0.2.1","v0.2.0","v0.1.7","v0.1.6","v0.1.5","v0.1.4","v0.1.3","v0.1.2","v0.1.1","v0.1.0","submission"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-73556.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}