CVE-2026-6607

lm-sys fastchat Worker API Endpoint api_generate resource consumption

State: Published
Severity: 6.9 Medium
Published: Apr 20, 2026
Updated: Apr 20, 2026
Reserved: Apr 19, 2026

Description

A security vulnerability has been detected in lm-sys fastchat up to 0.2.36. This issue affects the function api_generate of the component Worker API Endpoint. The manipulation leads to resource consumption. The attack can be initiated remotely. The exploit has been disclosed publicly and may be used. The identifier of the patch is c9e84b89c91d45191dc24466888de526fa04cf33. It is suggested to install a patch to address this issue. Commit ff66426 patched this issue in api_generate of base_model_worker.py and did miss other entry points.

Scores

CVSS	Score	Vector	Source
4.0	6.9 Medium	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P	VulDB
3.1	5.3 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C	VulDB
3.0	5.3 Medium	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C	VulDB
2.0	5.0 Medium	AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C	VulDB

Weaknesses

CWE-400 Resource Consumption
CWE-404 Denial of Service

Affected Products

Product	Versions
fastchatlm-sys	0.2.0Affected 0.2.1Affected 0.2.2Affected 0.2.3Affected 0.2.4Affected 0.2.5Affected 0.2.6Affected 0.2.7Affected 0.2.8Affected 0.2.9Affected 0.2.10Affected 0.2.11Affected 0.2.12Affected 0.2.13Affected 0.2.14Affected 0.2.15Affected 0.2.16Affected 0.2.17Affected 0.2.18Affected 0.2.19Affected 0.2.20Affected 0.2.21Affected 0.2.22Affected 0.2.23Affected 0.2.24Affected and 12 more versions

References

VDB-358242 | lm-sys fastchat Worker API Endpoint api_generate resource consumptionvdb-entrytechnical-description
VDB-358242 | CTI Indicators (IOB, IOC, TTP, IOA)signaturepermissions-required
Submit #792227 | LM-Sys FastChat <= 0.2.36 Denial of Service (CWE-400)third-party-advisory
https://github.com/lm-sys/FastChat/issues/3833issue-tracking
https://github.com/lm-sys/FastChat/pull/3835issue-trackingpatch
https://gist.github.com/YLChen-007/87216a2d97a882d619e11dc67cd473b5exploit
https://github.com/lm-sys/FastChat/commit/c9e84b89c91d45191dc24466888de526fa04cf33patch
https://github.com/lm-sys/FastChat/product

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