Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

4.6 · CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N · score source

EPSS

• CVE-2026-32946: 0.26% estimated exploitation activity in the next 30 days; percentile 17.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A vulnerability exists in the Community Tier of Harden-Runner that allows bypassing the egress-policy: block network restriction using DNS queries over TCP. Harden-Runner enforces egress policies on GitHub runners by filtering outbound connections at the network layer. When egress-policy: block is enabled with a restrictive allowed-endpoints list (e.g., only github.com:443), all non-compliant traffic should be denied. However, DNS queries over TCP, commonly used for large responses or fallback from UDP, are not adequately restricted. Tools like dig can explicitly initiate TCP-based DNS queries (+tcp flag) without being blocked. This vulnerability requires the attacker to already have code execution capabilities within the GitHub Actions workflow. The Enterprise Tier of Harden-Runner is not affected by this vulnerability. Impact When Harden-Runner is configured with egress-policy: block and a restrictive allowed-endpoints list, an attacker with existing code execution…

Published by the source

17 Mar 2026, 18:37 UTC

Last modified by the source

20 Mar 2026, 21:21 UTC

Source last checked

26 Oct 2026, 17:08 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-g699-3x6g-wm3g

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# Patch Next advisory brief: CVE-2026-32946

Advisory: Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)
IDs: CVE-2026-32946, GHSA-g699-3x6g-wm3g
Record: https://patchnext.com/advisories/cve-2026-32946 (revision 1, source checked 26 Oct 2026, 17:08 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: step-security/harden-runner 2.16.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- GitHub Actions step-security/harden-runner: affected <= 2.15.1; fixed in 2.16.0

## Suggested inspection (read-only)
- GitHub Actions step-security/harden-runner: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on step-security/harden-runner.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-g699-3x6g-wm3g (GitHub-reviewed advisory GHSA-g699-3x6g-wm3g lists affected ranges: GitHub Actions step-security/harden-runner >=0 <=2.15.1)

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