Description
In lm-sys/fastchat Release v0.2.36, the server fails to handle excessive characters appended to the end of multipart boundaries. This flaw can be exploited by sending malformed multipart requests with arbitrary characters at the end of the boundary. Each extra character is processed in an infinite loop, leading to excessive resource consumption and a complete denial of service (DoS) for all users. The vulnerability is unauthenticated, meaning no user login or interaction is required for an attacker to exploit this issue.
Scores
CVSS v3
7.5
EPSS
0.0090
EPSS Percentile
75.8%
Attack Vector
NETWORK
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-835
Status
published
Products (2)
lm-sys/fastchat
0.2.36
pypi/fschat
0PyPI
Published
Mar 20, 2025
Tracked Since
Feb 18, 2026