Resource exhaustion in Lm-Sys Fastchat
CVE-2026-6607
A security vulnerability has been detected in lm-sys fastchat up to 0.2.36. This issue affects the function api_generate of the component Worker API Endpoint. The manipulation leads to resource consumption. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used. The identifier of the patch is c9e84b89c91d45191dc24466888de526fa04cf33. It is suggested to install a patch to address this issue. Commit ff66426 patched this issue in api_generate of base_model_worker.py and did miss other entry points.
Vulnerability class: DoS (Denial of Service)
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: 0.007 (52.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 53rd percentile — 52.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001
Affected products
- Lm-Sys Fastchat — versions 0.2.0, 0.2.1, 0.2.2
Weakness classification (CWE)
References
- vuldb.com/vuln/358242 (technical-description, vdb-entry)
- vuldb.com/vuln/358242/cti (signature, permissions-required)
- vuldb.com/submit/792227 (third-party-advisory)
- github.com/lm-sys/FastChat/issues/3833 (issue-tracking)
- github.com/lm-sys/FastChat/pull/3835 (issue-tracking, patch)
- gist.github.com/YLChen-007/87216a2d97a882d619e11dc67cd473b5 (exploit)
- github.com/lm-sys/FastChat/commit/c9e84b89c91d45191dc24466888de526fa04cf33 (patch)
- github.com/lm-sys/FastChat/ (product)
Frequently asked questions
- What is CVE-2026-6607?
- CVE-2026-6607 is a medium-severity vulnerability in Lm-Sys Fastchat, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-04-20.
- How severe is CVE-2026-6607?
- Medium severity. CVSS v3 base score is 5.3 out of 10.