# CVE-2026-15996: Denial of service in Enterprise Server

> Unauthenticated attackers can cause denial of service in GitHub Enterprise Server by sending crafted requests with deeply nested parameters, exhausting worker processes.

- **Severity:** Medium 6.6 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 5 Aug 2026
- **Updated:** 6 Aug 2026
- **Also known as:** GHSA-3x3p-rpwc-h9wf

## What is CVE-2026-15996?

CVE-2026-15996 is a medium-severity denial of service vulnerability in Github Enterprise Server, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### 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.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-15996?

It affects 1 product.


Products: Github Enterprise Server.

## How do I fix CVE-2026-15996?

No fix has been published for CVE-2026-15996 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-15996 being exploited?

There is no known exploitation of CVE-2026-15996 in the wild and no public exploit code.

## Other vulnerabilities in Github Enterprise Server

- [CVE-2024-4985](https://insights.sbomify.com/CVE-2024-4985/): Auth bypass in Enterprise Server (critical 10.0)
- [CVE-2022-23739](https://insights.sbomify.com/CVE-2022-23739/): Missing authorization in GitHub Enterprise Server (critical 9.8)
- [CVE-2022-46255](https://insights.sbomify.com/CVE-2022-46255/): Improper Limitation of a Pathname to a Restricted Directory in GitHub Enterprise Server leading to RCE (critical 9.8)
- [CVE-2021-22869](https://insights.sbomify.com/CVE-2021-22869/): Improper access control in GitHub Enterprise Server allows self-hosted runners to execute outside their control group (critical 9.8)
- [CVE-2024-9487](https://insights.sbomify.com/CVE-2024-9487/): Auth bypass in Enterprise Server (critical 9.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-15996 and fix it if it is affected.

What it is: CVE-2026-15996 is a medium-severity denial of service vulnerability in Github Enterprise Server, published on 5 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-15996 in the wild and no public exploit code.

Affected product: Github Enterprise Server. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-15996/ (Markdown: https://insights.sbomify.com/CVE-2026-15996/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-15996
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-15996
- OSV: https://osv.dev/vulnerability/CVE-2026-15996

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-15996/
Summaries are generated and may contain mistakes; the official description above is the record.