lm-sys fastchat apply_delta.py apply_delta_low_cpu_mem deserialization
Priority LOW 21CWE-20Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Code execution
- Confidentiality · integrity · availability
- Low · Low · Low
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-502.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00206 10th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| lm-sys | fastchat | 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 | — | No fix listed | CNA |
- fastchat Vendorlm-sys Affected 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 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2025-3677
- 2026-10-03 Alias added: GHSA-v32v-5787-25w8
References
More lm-sys vulnerabilities
- TI-2024-09320 SSRF in POST /worker_generate_stream API endpoint in lm-sys/fastchat CVSS 3.0CRITICAL 9.3
- TI-2024-11482 Server Side Request Forgery in lm-sys/fastchat CVSS 3.0HIGH 7.5
- TI-2024-10750 Server-Side Request Forgery in lm-sys/fastchat CVSS 3.0HIGH 7.5
- TI-2024-10115 Denial of Service in lm-sys/fastchat CVSS 3.0HIGH 7.5
- TI-2024-10111 Denial of Service (DoS) via Multipart Boundary in lm-sys/fastchat CVSS 3.0HIGH 7.5
- TI-2026-05795 lm-sys fastchat Arena Side-by-Side View add_text control flow CVSS 4.0MEDIUM 6.9
Sources
- CVE-2025-3677 · CVE Program
- CVE-2025-3677 · NVD
- FIRST EPSS
- GHSA-v32v-5787-25w8 · GitHub Advisory Database · CC BY 4.0
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