Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
vLLM versions 0.8.0 up to but not including 0.9.0 are affected. A client that sends an invalid regex while using structured output can crash the OpenAI-compatible server, causing a denial of service. The source gives few details about the required access level. Upgrade vLLM to version 0.9.0 or later.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 6.5 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0051, the 43rd percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:40 UTC First seen by agentprime
- 31 Oct 2026, 14:40 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-9hcf-v7m4-6m2j
- OSV: GHSA-9hcf-v7m4-6m2j
- github.com/vllm-project/vllm/security/advisories/GHSA-9hcf-v7m4-6m2j
- nvd.nist.gov/vuln/detail/CVE-2025-48943
- github.com/vllm-project/vllm/issues/17313
- github.com/vllm-project/vllm/pull/17623
- github.com/vllm-project/vllm/commit/08bf7840780980c7568c573c70a6a8db94fd45ff
- github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2025-55.yaml
- github.com/vllm-project/vllm