GHSA-hf3c-wxg2-49q9 – vllm
Package
Manager: pip
Name: vllm
Vulnerable Version: >=0.6.5 <0.8.4
Severity
Level: Medium
CVSS v3.1: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS: N/A pctlN/A
Details
vLLM vulnerable to Denial of Service by abusing xgrammar cache ### Impact This report is to highlight a vulnerability in XGrammar, a library used by the structured output feature in vLLM. The XGrammar advisory is here: https://github.com/mlc-ai/xgrammar/security/advisories/GHSA-389x-67px-mjg3 The [xgrammar](https://xgrammar.mlc.ai/docs/) library is the default backend used by vLLM to support structured output (a.k.a. guided decoding). Xgrammar provides a required, built-in cache for its compiled grammars stored in RAM. xgrammar is available by default through the OpenAI compatible API server with both the V0 and V1 engines. A malicious user can send a stream of very short decoding requests with unique schemas, resulting in an addition to the cache for each request. This can result in a Denial of Service by consuming all of the system's RAM. Note that even if vLLM was configured to use a different backend by default, it is still possible to choose xgrammar on a per-request basis using the `guided_decoding_backend` key of the `extra_body` field of the request with the V0 engine. This per-request choice is not available when using the V1 engine. ### Patches * https://github.com/vllm-project/vllm/pull/16283 ### Workarounds There is no way to workaround this issue in existing versions of vLLM other than preventing untrusted access to the OpenAI compatible API server. ### References * https://github.com/mlc-ai/xgrammar/security/advisories/GHSA-389x-67px-mjg3
Metadata
Created: 2025-04-15T21:21:04Z
Modified: 2025-04-15T21:21:04Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2025/04/GHSA-hf3c-wxg2-49q9/GHSA-hf3c-wxg2-49q9.json
CWE IDs: ["CWE-1395", "CWE-770"]
Alternative ID: N/A
Finding: F067
Auto approve: 1