Harden-Runner is a CI/CD security agent that works like an EDR for GitHub Actions runners. In versions 2.15.1 and below, a DNS over HTTPS (DoH) vulnerability allows attackers to bypass egress-policy: block network restrictions by tunneling exfiltrated data through permitted HTTPS endpoints like dns.google. The attack works by encoding sensitive data (e.g., the runner's hostname) as subdomains in DoH queries, which appear as legitimate HTTPS traffic to Harden-Runner's domain-based filtering but are ultimately forwarded to an attacker-controlled domain. This effectively enables data exfiltration without directly connecting to any blocked destination. Exploitation requires the attacker to already have code execution within the GitHub Actions workflow. The issue was fixed in version 2.16.0.

Project Subscriptions

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-46g3-37rh-v698 Egress Policy Bypass via DNS over HTTPS (DoH) in Harden-Runner (Community Tier)
Fixes

Solution

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Workaround

No workaround given by the vendor.

History

Fri, 20 Mar 2026 04:45:00 +0000

Type Values Removed Values Added
Description Harden-Runner is a CI/CD security agent that works like an EDR for GitHub Actions runners. In versions 2.15.1 and below, a DNS over HTTPS (DoH) vulnerability allows attackers to bypass egress-policy: block network restrictions by tunneling exfiltrated data through permitted HTTPS endpoints like dns.google. The attack works by encoding sensitive data (e.g., the runner's hostname) as subdomains in DoH queries, which appear as legitimate HTTPS traffic to Harden-Runner's domain-based filtering but are ultimately forwarded to an attacker-controlled domain. This effectively enables data exfiltration without directly connecting to any blocked destination. Exploitation requires the attacker to already have code execution within the GitHub Actions workflow. The issue was fixed in version 2.16.0.
Title Egress Policy Bypass via DNS over HTTPS (DoH) in Harden-Runner (Community Tier)
Weaknesses CWE-693
CWE-863
References
Metrics cvssV4_0

{'score': 4.6, 'vector': '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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-03-20T04:03:03.687Z

Reserved: 2026-03-17T00:05:53.284Z

Link: CVE-2026-32947

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-03-20T05:16:13.923

Modified: 2026-03-20T05:16:13.923

Link: CVE-2026-32947

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses