Authorization bypass through user-controlled key in vLLM - CVE-2026-105755

Vulnerability details

The vulnerability allows a low-privileged remote attacker to corrupt another user's scoring or reranking results and induce transient request errors.

The vulnerability exists due to vLLM's use of caller-controlled X-Request-Id values as query embedding cache keys for /score and /rerank when flash late interaction is enabled. A low-privileged remote attacker can reuse a known victim request identifier in a concurrent request to overwrite cached embeddings, causing the victim's documents to be scored against the attacker's query.

Affected software

How to mitigate CVE-2026-105755

External References

• https://github.com/vllm-project/vllm/security/advisories/GHSA-2phq-3phc-84px

Related Security Bulletins

• Multiple vulnerabilities in vLLM