Vulnerability in GitHub Enterprise Server
CVE-2026-15996
A denial of service vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to cause excessive CPU consumption and exhaust the pool of request-handling worker processes by sending a crafted form-encoded HTTP POST request containing deeply nested parameters. Because request parameters were parsed before routing and authentication, any POST endpoint could be used to trigger the condition, which could render the instance unresponsive. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.21 and was fixed in versions 3.20.3, 3.19.7, 3.18.10, and 3.17.16.
EPSS: 0.004 (37.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Github Enterprise Server — versions 3.17.0, 3.18.0, 3.19.0
- Github Enterprise_server
Weakness classification (CWE)
References
- product-cna@github.com (release-notes, Product, Release Notes)
- product-cna@github.com (release-notes, Product, Release Notes)
- product-cna@github.com (release-notes, Product, Release Notes)
- product-cna@github.com (release-notes, Product, Release Notes)
Frequently asked questions
- What is CVE-2026-15996?
- CVE-2026-15996 is a high-severity vulnerability in GitHub Enterprise Server, classified under Uncontrolled Recursion. CVSS score: 7.5/10. Published 2026-08-05.
- How severe is CVE-2026-15996?
- High severity. CVSS v3 base score is 7.5 out of 10.