CVE-2025-3677

lm-sys fastchat apply_delta.py apply_delta_low_cpu_mem deserialization

4.8 Medium

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.

Attack profile

How easy it is to exploit

Attack vector: Local
Complexity: Low
Privileges needed: Low
User interaction: None

What an attacker can affect

Confidentiality: Low
Integrity: Low
Availability: Low

Exploit likelihood

0.21%Up 0.2 points since Apr 16, 2025

What each source reports

CVE List Score used 4.8

lm-sys fastchat apply_delta.py apply_delta_low_cpu_mem deserialization

Record: CVE-2025-3677
CVSS 4.0: 4.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CVSS 3.0: 5.3 MediumCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CVSS 2.0: 4.3 AV:L/AC:L/Au:S/C:P/I:P/A:P
Weakness: CWE-502, CWE-20
Updated: 2026-11-02

EUVDEUVD-2025-11794 4.8

Record: EUVD-2025-11794
CVSS 4.0: 4.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
Updated: 2026-11-02

GitHub AdvisoriesGHSA-v32v-5787-25w8 4.8

A vulnerability classified as critical was found in lm-sys fastchat up to 0.2.36. This...

Record: GHSA-v32v-5787-25w8
CVSS 4.0: 4.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
Weakness: CWE-20
Updated: 2026-11-02

NVD 4.8

Record: CVE-2025-3677
CVSS 4.0: 4.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1: 5.3 MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CVSS 2.0: 4.3 MediumAV:L/AC:L/Au:S/C:P/I:P/A:P
Weakness: CWE-20, CWE-502
Updated: 2026-11-02

OSV 4.8

lm-sys fastchat apply_delta.py apply_delta_low_cpu_mem deserialization

Record: CVE-2025-3677
CVSS 4.0: 4.8 MediumCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N
Weakness: CWE-20, CWE-502
Updated: 2026-11-02

Affected products

lm-sys fastchat

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-3677 is a medium vulnerability (CVSS 4.8) in Lm-sys Fastchat, published April 16, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.21%, the 10th percentile. No source names a fixed version.