CVE-2025-3677: lm-sys fastchat apply_delta.py apply_delta_low_cpu_mem deserialization

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-16 · updated 2026-06-17
Weakness: CWE-20

Description

A vulnerability classified as critical was found in lm-sys fastchat up to 0.2.36. This vulnerability affects the function split_files/apply_delta_low_cpu_mem of the file fastchat/model/apply_delta.py. The manipulation leads to deserialization. An attack has to be approached locally.

Affected products

lm-sys/fastchat: 0.2.0, 0.2.1, 0.2.2, 0.2.3, 0.2.4, 0.2.5 (+31)

References

https://github.com/lm-sys/FastChat/issues/3713
https://vuldb.com/?ctiid.304966
https://vuldb.com/?id.304966
https://vuldb.com/?submit.552755

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