What is CVE-2026-15976?

CVE-2026-15976 is a critical-severity vulnerability in Lmsys Sglang, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-07-30.

How severe is CVE-2026-15976?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Deserialization in Lmsys Sglang

CVE-2026-15976

SGLang contains a RCE vulnerability when attempting to load model weights from a HuggingFace repository, specifically within the /update_weights_from_disk, where torch.load(..., weights_only=False) fallback enables pickle deserialization of .bin files.

Vulnerability class: Insecure Deserialization

EPSS: 0.005 (40.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Lmsys Sglang
Sglang — versions 0

Weakness classification (CWE)

CWE-502 — Deserialization of Untrusted Data

References

cret@cert.org (Broken Link)
cret@cert.org (Third Party Advisory, Mitigation)

Frequently asked questions

What is CVE-2026-15976?: CVE-2026-15976 is a critical-severity vulnerability in Lmsys Sglang, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-07-30.
How severe is CVE-2026-15976?: Critical severity. CVSS v3 base score is 9.8 out of 10.