CVE-2026-15783: Auth Bypass

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.

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EPSS — Exploit Prediction

0.0027

Probability of exploitation

0.19%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-862 Missing Authorization

References

Other References

https://docs.github.com/en/[email protected]/admin/release-notes#3.17.18 https://docs.github.com/en/[email protected]/admin/release-notes#3.18.12 https://docs.github.com/en/[email protected]/admin/release-notes#3.19.9 https://docs.github.com/en/[email protected]/admin/release-notes#3.20.5 https://docs.github.com/en/[email protected]/admin/release-notes#3.21.3

Frequently Asked Questions

What is CVE-2026-15783? +

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.

How do I check if I'm vulnerable to CVE-2026-15783? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-15783