CVE-2026-5845 json
Improper authorization fallback allows scoped user-to-server token installation escape in GitHub Enterprise Server
published 2026-04-21 6 mo ago modified 2026-10-26 13 d ago also EUVD-2026-24552
- cvss
- 9.6
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 21%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- GitHub Enterprise Server 3.14.26, 3.15.21, 3.16.17, 3.17.14, 3.18.8, 3.19.5, 3.20.1
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 6 mo ago
Exploit prediction
0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 7.2 | 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 |
| CNA | 4.0 | 7.2 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 9.6 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N |
Affected products
- GitHub Enterprise Server
Classification
- Weakness
-
- CWE-639 Authorization Bypass Through User-Controlled Key
References
-
docs.github.com
/en/enterprise-server@3.20/admin/release-notes#3.20.1
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.19/admin/release-notes#3.19.5
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.18/admin/release-notes#3.18.8
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.17/admin/release-notes#3.17.14
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.16/admin/release-notes#3.16.17
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.15/admin/release-notes#3.15.21
release-notes, vendor-advisory
-
docs.github.com
/en/enterprise-server@3.14/admin/release-notes#3.14.26
release-notes, vendor-advisory
Sources
- CVE List CVE-2026-5845
- NVD CVE-2026-5845
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