VulnerabilityAnalyzed

CVE-2026-103620

MEDIUM 6.0EPSS 0.50%

Does this matter?

Lower severity and a low EPSS score (0.50%). Track it; it rarely justifies an emergency change on its own.

Description

A 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.

CVSS 4.0: 6.0 MEDIUMCVSS: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/M
EPSS: 0.50% probability · 43th percentile
Public exploits: None in Exploit-DB
CISA KEV: Not listed
Weakness: CWE-862
Affected: github/enterprise server
Source: product-cna@github.com

EPSS trend

EPSS moved from 0.4% on 7 October 2026 to 0.5% on 26 October 2026.

References

https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.16Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.13Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.9Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.7Release Notes, Vendor Advisory
https://docs.github.com/en/enterprise-server@3.22/admin/release-notes#3.22.2Release Notes, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.