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.
https://vuldb.com/vuln/358243/cti
https://vuldb.com/submit/792228
https://github.com/lm-sys/FastChat/issues/3834
https://github.com/lm-sys/FastChat/
https://gist.github.com/YLChen-007/e45039d23e698222d887ee09735d9d36
Published: 2026-04-20
Updated: 2026-04-20
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N
Severity: Medium
Base Score: 5.3
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Severity: Medium
Base Score: 6.9
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
Severity: Medium