What is CVE-2026-15978?

CVE-2026-15978 is a high-severity vulnerability in Lmsys Sglang, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2026-07-30.

How severe is CVE-2026-15978?

High severity. CVSS v3 base score is 7.5 out of 10.

Auth bypass in Lmsys Sglang

CVE-2026-15978

SGLang contains a model weight exfiltration vulnerability when no API keys are configured, as SGLang will expose two endpoints that allow a remote attacker to trigger distributed weight broadcasting using NCCL and then triggering data transfer, attackers can exfiltrate all model weights.

Vulnerability class: Broken Authentication

Published 2026-07-30 · last modified 2026-08-04.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.005 (43.0th percentile), scored 2026-10-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 43.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Lmsys Sglang
Sglang — versions 0

Weakness classification (CWE)

CWE-306 — Missing Authentication for Critical Function

References

github.com/sgl-project/sglang/security/advisories/GHSA-cpqq-22v3-2wfm (Broken Link)
thoughts.apoorvdayal.com/posts/sglang-disclosures/ (Third Party Advisory, Mitigation)

Frequently asked questions

What is CVE-2026-15978?: CVE-2026-15978 is a high-severity vulnerability in Lmsys Sglang, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2026-07-30.
How severe is CVE-2026-15978?: High severity. CVSS v3 base score is 7.5 out of 10.