CVE-2026-5921: GitHub Enterprise Server

Server-Side Request Forgery in GitHub Enterprise Server allowed extraction of sensitive environment variables via timing side-channel attack

CVSS 8.9 HighEPSS 0.0042 · 36th percentile

Published by the CVE Program (CNA: GitHub_P) at 21 Apr 2026, 22:11 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
GitHub	Enterprise Server	affected 3.14.0 to before 3.14.26 semver affected 3.15.0 to before 3.15.21 semver affected 3.16.0 to before 3.16.17 semver affected 3.17.0 to before 3.17.14 semver affected 3.18.0 to before 3.18.8 semver affected 3.19.0 to before 3.19.5 semver affected 3.20.0 to before 3.20.1 semver Other versions: affected

Identifiers

CVE-2026-5921

CNA

GitHub_P

Weakness (CWE)

CWE-918

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
8.9	High	4.0	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:P	CNA (GitHub_P)

CISA KEV Not listed.
EPSS 0.0042, the 36th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 21 Apr 2026. New records show when each source confirmed them.

Sources

References from the CNA

docs.github.com/en/[email protected]/admin/release-notes#3.14.26 release-notes
docs.github.com/en/[email protected]/admin/release-notes#3.15.21 release-notes
docs.github.com/en/[email protected]/admin/release-notes#3.16.17 release-notes
docs.github.com/en/[email protected]/admin/release-notes#3.17.14 release-notes
docs.github.com/en/[email protected]/admin/release-notes#3.18.8 release-notes
docs.github.com/en/[email protected]/admin/release-notes#3.19.5 release-notes
docs.github.com/en/[email protected]/admin/release-notes#3.20.1 release-notes

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.