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fastchatGHSA-f3q6-69f3-vwch

FastChat has a Content Moderation Bypass via Arena Side-by-Side Views

Medium5.3CVE-2026-6608 · Published Apr 20, 2026 · updated Jul 13, 2026

GitHub advisory

Affected versions

PackageAffectedFixed in
fschat
PyPI
<= 0.2.36No fix yet
Details and references

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 exploit is now public and may be used. The root cause was fixed in commit 34eca62 for gradio_block_arena_named.py, but three other files were missed.

CVSS 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Severity from
GitHub (reviewed advisory)
Weakness
CWE-670
Also known as
CVE-2026-6608, PYSEC-2026-2485

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