Improper input validation in Vllm
CVE-2026-100647
vLLM versions before 0.29.0 contain a denial-of-service vulnerability in the cache_salt parameter accepted on OpenAI-compatible and Anthropic API endpoints, which lacks maximum length validation and is processed on the single EngineCore scheduler thread. Unauthenticated attackers can send HTTP requests with multi-hundred-megabyte salt values that trigger expensive pickle serialization and SHA-256 hashing, stalling the scheduler thread and denying service to all concurrent requests.
Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.003 (28.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 29th percentile — 28.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000
Affected products
Weakness classification (CWE)
References
- GitHub Security Advisory (GHSA-wpww-v874-ph2p) (vendor-advisory, Vendor Advisory)
- VulnCheck Advisory: vLLM before 0.29.0 CPU Exhaustion via unbounded cache_salt (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-100647?
- CVE-2026-100647 is a medium-severity vulnerability in Vllm, classified under Improper Input Validation. CVSS score: 5.3/10. Published 2026-09-26.
- How severe is CVE-2026-100647?
- Medium severity. CVSS v3 base score is 5.3 out of 10.