CVE-2026-15783: github enterprise_server Missing Authorization

Vulnerability summary

CVE-2026-15783 is a medium (CVSS 5.3) Missing Authorization vulnerability in github enterprise_server. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.7% of scored vulnerabilities.

Timeline

1. 17-07-2026
   PublishedVulnerability first disclosed.
2. 17-07-2026
   Last modifiedVulnerability information updated.

Description

A missing authorization vulnerability was identified in GitHub Enterprise Server that allowed an authenticated user with write access to any repository to read metadata from private repositories they did not have access to, including private repository owners and names, branch names, commit SHAs, commit messages, and the pushing actor. The delegated bypass endpoint resolved a rule suite directly from an attacker-supplied, encoded identifier without verifying that the requesting user could read the rule suite's repository, and because these identifiers are sequential an attacker could enumerate them across the instance. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.17.18, 3.18.12, 3.19.9, 3.20.5, and 3.21.3. This vulnerability was reported via the GitHub Bug Bounty program.

• CWE-862Missing AuthorizationThe product does not perform an authorization check when an actor attempts to access a resource or perform an action.