Vulnerability in Lm-sys Fastchat
CVE-2026-6608
A vulnerability was detected in lm-sys fastchat up to 0.2.36. Impacted is the function add_text of the component Arena Side-by-Side View Handler. The manipulation results in incorrect control flow. The attack can be launched remotely. The…
EPSS: 0.000 (15.7th percentile) — read the EPSS interpretation.
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:L/A:N/E:P/RL:X/RC:R.
Affected products
- Lm-sys Fastchat — versions 0.2.0, 0.2.1, 0.2.2
Weakness classification (CWE)
References
- VDB-358243 | lm-sys fastchat Arena Side-by-Side View add_text control flow (vdb-entry, technical-description)
- VDB-358243 | CTI Indicators (IOB, IOC, IOA) (signature, permissions-required)
- Submit #792228 | LM-Sys FastChat <= 0.2.36 Content Moderation Bypass (CWE-670) (third-party-advisory)
- github.com/lm-sys/FastChat/issues/3834 (issue-tracking)
- gist.github.com/YLChen-007/e45039d23e698222d887ee09735d9d36 (exploit)
- github.com/lm-sys/FastChat/ (product)
Frequently asked questions
- What is CVE-2026-6608?
- CVE-2026-6608 is a medium-severity vulnerability in Lm-sys Fastchat, classified under Always-Incorrect Control Flow Implementation. CVSS score: 5.3/10. Published 2026-04-20.
- How severe is CVE-2026-6608?
- Medium severity. CVSS v3 base score is 5.3 out of 10.