Enterprise Server: Authorization Bypass Through User-Controlled Key
CVE-2026-5845 is a critical-severity authorization bypass through user-controlled key vulnerability in Enterprise Server from GitHub, with a CVSS 3.1 base score of 9.6 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 3.20.1 as the first without the flaw, so updating Enterprise Server to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.29% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Enterprise Server to 3.20.1 or a later version.
- Read the advisory on docs.github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| GitHub | Enterprise Server | 3.20.0 up to, but not including, 3.20.1; 3.19.0 through 3.19.4; 3.18.0 through 3.18.7; 3.17.0 through 3.17.13; 3.16.0 through 3.16.16; 3.15.0 through 3.15.20; 3.14.0 through 3.14.25 | 3.20.1 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 7.2 | High | CNA (github.com) |
| CVSS 3.1 | 9.6 | Critical | NVD |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Authorization Bypass Through User-Controlled Key
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
How developers prevent this class of flaw
- For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
- Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
- Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
More Authorization Bypass Through User-Controlled Key vulnerabilities (CWE-639)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
- docs.github.com/en/[email protected]/admin/release-notes#3.14.26Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.15.21Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.16.17Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.17.14Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.18.8Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.19.5Release Notes
- docs.github.com/en/[email protected]/admin/release-notes#3.20.1Release Notes
Other vulnerabilities in Enterprise Server
- 7.7 High severity
- 8.8 High severity
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
- 7.4 High severity
Recent Authorization Bypass Through User-Controlled Key vulnerabilities
- 9.0 Critical severity
- 7.1 High severity
- 7.6 High severity
- 7.1 High severity
- 8.8 High severity
- 8.1 High severity
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