vLLM: Structured-output request errors escape the request boundary and terminate the shared EngineCore — engine-fatal denial of service (3 sites)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-105757: 0.31% estimated exploitation activity in the next 30 days; percentile 24.36 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Affected - Ecosystem / package: pip / vllm - Affected versions: vLLM ≤ 0.25.1 (confirmed on 0.25.1, commit 752a3a504485). The lower bound predates 0.25.1; maintainers can confirm how far back each path reaches. Summary Three structured-output request paths let an ordinary request reach a condition that raises an uncaught, engine-fatal exception instead of a per-request validation error. The failure is not confined to the request that caused it: it escapes into EngineCore's busy loop and triggers a fatal sendenginedead(), so one malformed structured-output request denies service to all concurrent and subsequent tenants of that engine. The requests are ordinary API calls; the client does not need any privileged configuration beyond the (often default) structured-output feature. The shared root cause is the absence of a per-request exception boundary around structured-output grammar/token handling: a value that should fail as a request-scoped validation error instead propagates as an…

Published by the source

5 Oct 2026, 23:42 UTC

Last modified by the source

8 Oct 2026, 10:10 UTC

Source last checked

26 Oct 2026, 13:55 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-85xf-c7hm-whqw

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-85xf-c7hm-whqw

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-85xf-c7hm-whqw

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# Patch Next advisory brief: CVE-2026-105757

Advisory: vLLM: Structured-output request errors escape the request boundary and terminate the shared EngineCore — engine-fatal denial of service (3 sites)
IDs: CVE-2026-105757, GHSA-85xf-c7hm-whqw
Record: https://patchnext.com/advisories/cve-2026-105757 (revision 3, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vllm 0.30.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI vllm: affected < 0.30.0; fixed in 0.30.0

## Suggested inspection (read-only)
- `python -m pip show vllm`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vllm.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-85xf-c7hm-whqw (GitHub-reviewed advisory GHSA-85xf-c7hm-whqw lists affected ranges: PyPI vllm >=0 <0.30.0)
- Verified: https://osv.dev/vulnerability/GHSA-85xf-c7hm-whqw (OSV record GHSA-85xf-c7hm-whqw lists affected ranges: PyPI vllm >=0 <0.30.0 (fixed))

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