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Medium

SGLang Remote Code Execution Vulnerability via Unsafe Deserialization in update_weights_from_tensor

  • Disclosed: 09.09.2025
  • Updated: 11.10.2026 13:19

A security flaw has been discovered in lmsys sglang 0.4.6. Affected by this vulnerability is the function main of the file /update_weights_from_tensor. The manipulation of the argument serialized_named_tensors results in deserialization. The attack can be launched remotely. The exploit has been released to the public and may be exploited. The vendor was contacted early about this disclosure but did not respond in any way.

Affected software

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PlatformPackageVulnerable versionsFixed in
Python (PyPI) sglang < 0.5.4 0.5.4

References

CVSS score 7.3/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Weakness (CWE)
CWE-20, CWE-502
Platform
Python (PyPI)
Package
sglang
Disclosed
09.09.2025
Updated
11.10.2026 13:19

Sources and licenses

OSV / GitHub Advisory Database - PYSEC-2026-1919 - PyPA Advisory Database; CC BY 4.0

OSV / GitHub Advisory Database - GHSA-9w53-xr52-mwgj - CC BY 4.0

Vulnerability history: sglang

All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (10) in the archive
Total entries
10
First → latest
09.2025 06.2026
Without a fix
6
Exploited in attacks
0

Severity breakdown

  • Critical 5
  • High 1
  • Medium 2
  • Low 2

Disclosures per year

Severity:
  1. SGLanG: Multimodal scheduler deserializes untrusted pickle data on 0.0.0.0 ROUTER socket
    Critical · 9.8 CVE-2026-7301 >= 0.5.5, <= 0.5.12 no fix
  2. SGLang's multimodal generation runtime has an unauthenticated path traversal vulnerability
    Critical · 9.1 CVE-2026-7302 >= 0.5.5, <= 0.5.12 no fix
  3. SGLang: Unauthenticated RCE via --enable-custom-logit-processor
    Critical · 9.8 CVE-2026-7304 >= 0.4.1.post7, <= 0.5.12 no fix
  4. SGLangs `replay_request_dump.py` contains an insecure pickle.load() without validation and proper deserialization
    High · 7.8 CVE-2026-3989 < 0.5.10 0.5.10
  5. SGLang's multimodal generation module is vulnerable to unauthenticated remote code execution through the ZMQ broker
    Critical · 9.8 CVE-2026-3059 < 0.5.10 0.5.10
  6. SGLang's encoder parallel disaggregation system is vulnerable to unauthenticated remote code execution through the disaggregation module
    Critical · 9.8 CVE-2026-3060 < 0.5.10 0.5.10
  7. SGLang Remote Code Execution Vulnerability via Unsafe Deserialization in update_weights_from_tensor this entry
    Medium · 7.3 CVE-2025-10164 < 0.5.4 0.5.4

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