{"id":"PYSEC-2026-4344","details":"vLLM is an inference and serving engine for large language models. From 0.19.0 until 0.32.0, authenticated callers can supply a request chat template when no server-side --chat-template is configured, or a malicious model repository can provide a template that is compiled and rendered by tokenizer.apply_chat_template() without a wall-clock timeout, output-size limit, or iteration bound. Rendering runs in a ThreadPoolExecutor with one worker by default, so a nonterminating render can block /v1/responses and other chat-template users after the request ends, while an output-expanding render can exhaust server memory. Harmony models are not affected because they do not use this Jinja path. This issue is fixed in version 0.32.0.","aliases":["CVE-2026-115911","GHSA-542m-9234-8gvf"],"modified":"2026-10-29T11:00:02.788141501Z","published":"2026-10-26T17:17:18.753Z","references":[{"type":"ADVISORY","url":"https://github.com/vllm-project/vllm/releases/tag/v0.32.0"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/commit/cff08b461e086523cee8bba5bd3c66d302625134"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/pull/50300"},{"type":"FIX","url":"https://github.com/vllm-project/vllm/security/advisories/GHSA-542m-9234-8gvf"}],"affected":[{"package":{"name":"vllm","ecosystem":"PyPI","purl":"pkg:pypi/vllm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0.19.0"},{"fixed":"0.32.0"}]}],"versions":["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","0.24.0","0.25.0","0.25.1","0.26.0","0.27.0","0.27.1","0.28.0","0.29.0","0.30.0","0.31.0"],"ecosystem_specific":{},"database_specific":{"source":"https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-4344.yaml"}}],"schema_version":"1.9.2","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}