CVE-2026-105755: vLLM Cross-Request Integrity Break via Caller-Controlled Request ID
Summary
CVE-2026-105755: Affected - Ecosystem / package: pip / vllm - Affected versions: vLLM ≤ 0.25.1 (confirmed on 0.25.1, commit 752a3a504485). Affects vllm versions < 0.30.0. Fixed in 0.30.0. How to fix ↓
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Background
vLLM is a high-performance library designed for efficient large language model serving, enabling late-interaction scoring and reranking of queries. It is widely used in machine learning applications for its ability to handle concurrent requests efficiently. However, a vulnerability exists in versions up to 0.25.1, where the caching mechanism for query embeddings can be manipulated through a caller-controlled request ID, leading to potential data integrity issues.
Vulnerability Detail
The vulnerability arises from the way vLLM handles the caching of query embeddings during late-interaction scoring and reranking. Specifically, the system caches these embeddings using a key derived from the 'X-Request-Id' header, which can be controlled by the caller. This allows an attacker to reuse a victim's request ID, resulting in their query embedding overwriting the victim's cached entry. Consequently, the victim's documents are scored against the attacker's query, leading to a cross-request integrity break. Additionally, this can induce errors if the shared use counter is exhausted, forcing the victim's request into a cache-miss error. The vulnerability is confirmed in version 0.25.1 and potentially affects earlier versions.
How To Fix
Latest published version: 0.32.0 as of 22 Oct 2026
pip install --upgrade "vllm==0.32.0"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
0.30.0
This is the first release that contains the fix.
pip install --upgrade "vllm==0.30.0"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can disable flash late interaction if possible, or ensure that your application does not allow the reuse of 'X-Request-Id' values across different requests.
Conclusion
The vulnerability CVE-2026-105755 in vLLM poses significant risks to data integrity through cross-request manipulation of cached query embeddings. Users are advised to update to version 0.30.0 or later to mitigate these risks and ensure secure operation of their applications.
See every vulnerability recorded for vllm →
FAQ
The vulnerability allows an attacker to corrupt another user's results by reusing their request ID, leading to incorrect scoring of documents.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
Versions of vLLM up to and including 0.25.1 are affected by this vulnerability.
Yes, a patch is available in version 0.30.0 and later. It is recommended to update to this version to mitigate the vulnerability.
The CVSS score of this vulnerability is 4.2, indicating a moderate severity level.
References
Related vulnerabilities
Recent vulnerabilities recorded for vllm.
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