CVE-2025-3677 lm-sys fastchat apply_delta.py apply_delta_low_cpu_mem deserialization
A local attacker can exploit unsafe deserialization in fastchat's apply_delta.py to execute arbitrary code.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2025-3677?
CVE-2025-3677 is a medium-severity unsafe deserialization vulnerability in lm-sys fastchat, published on 16 Apr 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2025-3677?
How do I fix CVE-2025-3677?
No fix has been published for CVE-2025-3677 yet. Limit exposure of the affected software until one is available.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-3677 being exploited?
There is no known exploitation of CVE-2025-3677 in the wild and no public exploit code.
Sources
Also known as GHSA-v32v-5787-25w8.