What’s Vulnerable › Vulnerabilities

CVE-2026-105759: vLLM: Unbounded Prometheus label cardinality from attacker-controlled HTTP method tokens in the vLLM Rust frontend metrics middleware (unauthenticated denial of service)

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-10-05 · updated 2026-10-16
• Weakness: CWE-400

Description

vLLM is an inference and serving engine for large language models. Prior to 0.30.0, the Rust frontend's track_http_metrics middleware records the raw HTTP method token as a Prometheus label for requests reaching registered routes. An unauthenticated attacker can send unique arbitrary method tokens to unguarded routes such as /tokenize, causing Prometheus's Family::get_or_create function to permanently create counter and histogram label sets. Those label sets increase process memory usage and enlarge the /metrics response until the service or monitoring path is exhausted. This issue is fixed in version 0.30.0.

Affected products

• vllm-project vllm: before 0.30.0 — fixed in 0.30.0

How to fix

Upgrade to a fixed version: vllm-project vllm 0.30.0. Check the vendor advisory for mitigations.

References

• https://github.com/vllm-project/vllm/commit/3735c2d5f5248259482b9045c34fb7a8a3892352
• https://github.com/vllm-project/vllm/pull/56058
• https://github.com/vllm-project/vllm/releases/tag/v0.30.0
• https://github.com/vllm-project/vllm/security/advisories/GHSA-5fj9-pfhr-6j48
• https://github.com/vllm-project/vllm/security/advisories/GHSA-5fj9-pfhr-6j48

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