CVE-2026-103620
MEDIUM 6A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed a repository collaborator with write access to delete the current default branch through the GraphQL API and cause an attacker-controlled branch to become the new default. In repositories that required pull-request review but did not restrict branch deletion, this bypassed the review requirement and caused fresh clones and default-branch API requests to use attacker-controlled content. This vulnerability affected supported GitHub Enterprise Server releases in the 3.18, 3.19, 3.20, 3.21, and 3.22 series and was fixed in versions 3.18.16, 3.19.13, 3.20.9, 3.21.7, and 3.22.2. This vulnerability was reported via the GitHub Bug Bounty program.
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.5%chance of exploitation in 30 days · 43rd percentile
Impact if exploited
6CVSS 4.0 · MEDIUM
- ConfidentialityNone
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ⚠Privileges: Requires a low-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ⚠Requirements: Specific conditions must be present
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
Search for new PoCs
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Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.
Data snapshot:
Weakness (CWE)
- CWE-862: Missing Authorization
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
References and research data (JSON)
Known Affected Software Configurations
| Vendor | Product | Version range |
|---|---|---|
| Github | Enterprise Server | ≥ 3.18.0 and < 3.18.16 |
| Github | Enterprise Server | ≥ 3.19.0 and < 3.19.13 |
| Github | Enterprise Server | ≥ 3.20.0 and < 3.20.9 |
| Github | Enterprise Server | ≥ 3.21.0 and < 3.21.7 |
| Github | Enterprise Server | ≥ 3.22.0 and < 3.22.2 |
All CVSS metrics
- MEDIUM 6 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N - MEDIUM 6 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/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 - MEDIUM 6.5 v3.1 · NVD Primary
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
References
Patches & mitigations
- https://docs.github.com/en/[email protected]/admin/release-notes#3.18.16 CVE record · GitHub_P · Updated 2026-10-06T18:56:41.101Z
NVD · CVE-2026-103620 · Updated 2026-10-20T19:33:53.047 - https://docs.github.com/en/[email protected]/admin/release-notes#3.19.13 CVE record · GitHub_P · Updated 2026-10-06T18:56:41.101Z
NVD · CVE-2026-103620 · Updated 2026-10-20T19:33:53.047 - https://docs.github.com/en/[email protected]/admin/release-notes#3.20.9 CVE record · GitHub_P · Updated 2026-10-06T18:56:41.101Z
NVD · CVE-2026-103620 · Updated 2026-10-20T19:33:53.047 - https://docs.github.com/en/[email protected]/admin/release-notes#3.21.7 CVE record · GitHub_P · Updated 2026-10-06T18:56:41.101Z
NVD · CVE-2026-103620 · Updated 2026-10-20T19:33:53.047 - https://docs.github.com/en/[email protected]/admin/release-notes#3.22.2 CVE record · GitHub_P · Updated 2026-10-06T18:56:41.101Z
NVD · CVE-2026-103620 · Updated 2026-10-20T19:33:53.047
Advisories
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-93666 EUVD · EUVD-2026-93666