lm-sys fastchat up to 0.2.36 apply_delta.py split_files/apply_delta_low_cpu_mem deserialization

Summaryinfo

A vulnerability was found in lm-sys fastchat up to 0.2.36 and classified as critical. This affects the function split_files/apply_delta_low_cpu_mem of the file fastchat/model/apply_delta.py. Executing a manipulation can lead to deserialization. This vulnerability is handled as CVE-2025-3677. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

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 with an unknown input leads to a deserialization vulnerability. The CWE definition for the vulnerability is CWE-502. The product deserializes untrusted data without sufficiently verifying that the resulting data will be valid. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was released with StarMap Team of Legendsec at QI-ANXIN Group as 3713. The advisory is available at github.com. This vulnerability was named CVE-2025-3677. The exploitation appears to be easy. Local access is required to approach this attack. Technical details are known, but there is no available exploit.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Chat Software

Vendor

• lm-sys

Name

• fastchat

Version

• 0.2.0
• 0.2.1
• 0.2.2
• 0.2.3
• 0.2.4
• 0.2.5
• 0.2.6
• 0.2.7
• 0.2.8
• 0.2.9
• 0.2.10
• 0.2.11
• 0.2.12
• 0.2.13
• 0.2.14
• 0.2.15
• 0.2.16
• 0.2.17
• 0.2.18
• 0.2.19
• 0.2.20
• 0.2.21
• 0.2.22
• 0.2.23
• 0.2.24
• 0.2.25
• 0.2.26
• 0.2.27
• 0.2.28
• 0.2.29
• 0.2.30
• 0.2.31
• 0.2.32
• 0.2.33
• 0.2.34
• 0.2.35
• 0.2.36

Website

• Product: https://github.com/lm-sys/FastChat/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Submitinfo

Accepted

• Submit #552755: lm-sys FastChat v0.2.3 to v0.2.36 Deserialization (by ybdesire)

Duplicate

• Submit #XXXXXX: Xx-xxx Xxxxxxxx ≤ X.x.xx（“xx Xx X.x.xx”） Xxxxxxxxxxxxxxx Xx Xxxxxxxxx Xxxx;xxxxxxxx Xxxxx Xxxxxxxxxx (by Tianrui Song)

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