CVE-2026-6608: FastChat has a Content Moderation Bypass via Arena Side-by-Side Views

CVE-2026-6608 · Severity: medium · CVSS 5.3 · Published 2026-04-20

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.

Technologies: fschat (PyPI). Vendors: PyPI.

Quick answers

Is CVE-2026-6608 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-6608 being exploited in the wild.
How severe is CVE-2026-6608?
Medium severity, with a CVSS score of 5.3, published 20 April 2026.
Which products and versions are affected?
fschat (PyPI) <= 0.2.36, ECOSYSTEM:introduced=0,last_affected=0.2.36.
Is there a fix for CVE-2026-6608?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
Am I affected by CVE-2026-6608?
Check whether you run fschat (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Affected products

  • fschat (PyPI) <= 0.2.36, ECOSYSTEM:introduced=0,last_affected=0.2.36

Identifiers

  • CVE-2026-6608
  • GHSA-f3q6-69f3-vwch
  • PYSEC-2026-2485

References

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