CVE-2026-5845CWE-639

Improper authorization fallback allows scoped user-to-server token installation escape in GitHub Enterprise Server

High · published April 21, 2026

CVSS v4.0
7.2
EPSS
0%
Percentile
40.4
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
7.2 · HIGH
Vector
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:L/SI:L/SA:N
EPSS
0.00479 · 40.4th percentile
Weakness
CWE-639 · Authorization Bypass Through User-Controlled Key
Published
2026-04-21T22:42Z
EPSS history
Timeline
  • 21 APR 22:42Z
    Improper authorization fallback allows scoped user-to-server token installation escape in GitHub Enterprise Server
    cvelistv5