Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The vLLM package, versions from 0.1.0 before 0.19.0, has a denial of service flaw in its OpenAI-compatible API server: the `n` parameter in chat and completion requests has no upper bound. An unauthenticated remote attacker can send a single HTTP request with a very large `n` value, which blocks the event loop and drives memory use up until the process is killed by the operating system. The source gives few details on any workaround. Upgrade vLLM to version 0.19.0 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 0.0044, the 38th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:34 UTC First seen by agentprime
- 31 Oct 2026, 14:34 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-3mwp-wvh9-7528
- OSV: GHSA-3mwp-wvh9-7528
- github.com/vllm-project/vllm/security/advisories/GHSA-3mwp-wvh9-7528
- nvd.nist.gov/vuln/detail/CVE-2026-34756
- github.com/vllm-project/vllm/pull/37952
- github.com/vllm-project/vllm/commit/b111f8a61f100fdca08706f41f29ef3548de7380
- access.redhat.com/errata/RHSA-2026:36005
- access.redhat.com/errata/RHSA-2026:36006
- access.redhat.com/security/cve/CVE-2026-34756
- bugzilla.redhat.com/show_bug.cgi?id=2455425
- github.com/pypa/advisory-database/tree/main/vulns/vllm/PYSEC-2026-2298.yaml
- github.com/vllm-project/vllm
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34756.json