vLLM: DoS via unbounded chat_template Jinja2 rendering exhausts the renderer thread pool (vllm-project vllm)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.31 % · percentile 24 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
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.
Weaknesses (CWE)
- CWE-400 — Uncontrolled Resource Consumption
- CWE-770 — Allocation of Resources Without Limits or Throttling
- CWE-834 — Excessive Iteration
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | GitHub_M |
| CVSS 3.1 | MEDIUM 6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | NVD · security-advisories@github.com (Secondary) |
Advisories
- GHSA-542m-9234-8gvf — vLLM: DoS via unbounded chat_template Jinja2 rendering exhausts the renderer thread pool
European references
- ENISA EUVD · EUVD-2026-109996
- GCVE · GCVE-0-2026-115911
Affected configurations (NVD CPE)
cpe:2.3:a:vllm:vllm:*:*:*:*:*:*:*:*≥ 0.19.0 < 0.32.0
Affected products
| Product | Versions |
|---|---|
| vllm-project · vllm | affected >= 0.19.0, < 0.32.0 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |