CVE-2026-5845: GitHub Enterprise Server broken access control (CVSS 9.6)

Description

An improper authorization vulnerability in scoped user-to-server (ghu_) token authorization in GitHub Enterprise Server allows an authenticated attacker to access private repositories outside the intended installation scope, which can include write operations, via an authorization fallback that treated a revoked/deleted installation as a global installation context, which could be chained with token revocation timing and SSH push attribution to obtain and reuse a victim-scoped token. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.1, 3.19.5, 3.18.8, 3.17.14, 3.16.17, 3.15.21, and 3.14.26. This vulnerability was reported via the GitHub Bug Bounty program.

CVSS 3.1 breakdown

Attack vectorNetwork

Attack complexityLow

Privileges requiredLow

User interactionNone

ScopeChanged

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected products

GitHub Enterprise Server≥ 3.15.0 < 3.15.21 · ≥ 3.16.0 < 3.16.17 · ≥ 3.17.0 < 3.17.14 · ≥ 3.18.0 < 3.18.8

Remediation

Fixed in

GitHub Enterprise Server≥ 3.15.21

Patch & vendor advisories

References

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

Related CVEs

Recent high-severity vulnerabilities sharing a weakness type.

Frequently asked

Is CVE-2026-5845 being actively exploited?

CVE-2026-5845 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.48%.

How severe is CVE-2026-5845?

CVE-2026-5845 has a CVSS 3.1 base score of 9.6, rated critical. EPSS estimates a 0.48% probability of exploitation.

Which products are affected by CVE-2026-5845?

Affected products include GitHub Enterprise Server.

How do I fix CVE-2026-5845?

Upgrade affected software to a fixed version, for example GitHub Enterprise Server 3.15.21 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-5845 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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