Medium severity · published Jul 17, 2026
CVE-2026-15783
Missing Authorization vulnerability was identified in GitHub Enterprise Server that allowed reading private repository metadata via delegated bypass rule suites
5.3
CVSS
0.4%
EPSS
No
On KEV
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.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 39% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ES
Enterprise Server · GitHub
3.17.0 through 3.17.17; 3.18.0 through 3.18.11; 3.19.0 through 3.19.8; 3.20.0 through 3.20.4; 3.21.0 through 3.21.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-15783
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-15783
docs.github.com
https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.18
docs.github.com
https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.12
docs.github.com
https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.9
docs.github.com
https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.5
docs.github.com
https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.3
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