CVE-2026-5845

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 v3.1 Score

9.6

CRITICAL

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

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.06%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-639 CWE-639

Affected Products

Vendor	Product	Versions
github	enterprise_server	< 3.14.26
github	enterprise_server	3.15.0 — 3.15.21
github	enterprise_server	3.16.0 — 3.16.17
github	enterprise_server	3.17.0 — 3.17.14
github	enterprise_server	3.18.0 — 3.18.8
github	enterprise_server	3.19.0 — 3.19.5
github	enterprise_server	All

References

Advisories & Patches

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

Frequently Asked Questions

What is CVE-2026-5845? +

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. It has a CVSS v3.1 base score of 9.6 (CRITICAL).

How severe is CVE-2026-5845? +

CVE-2026-5845 has a CVSS v3.1 score of 9.6 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-5845? +

CVE-2026-5845 affects products from github, specifically: enterprise_server. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-5845? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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