Vulnerability · Published Aug 5, 2026 · Assigned by GitHub_P
CVE-2026-15996Denial of service vulnerability in GitHub Enterprise Server allowed unauthenticated service disruption via deeply nested request parameters
Medium 6.6
In plain English
A medium-severity security flaw in Enterprise Server from GitHub. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.8% (higher than 56% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| GitHub | Enterprise Server | 3.17.0 – through 3.17.153.18.0 – through 3.18.93.19.0 – through 3.19.63.20.0 – through 3.20.2 |
Weakness: CWE-674 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U
References
- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.16 release-notes
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.10 release-notes
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.7 release-notes
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.3 release-notes