CVE-2026-32947

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.

CVSS v3 4.9 MEDIUM

4.9^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.2 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required HIGH

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/step-security/harden-runner/releases/tag/v2.16.0	Product Release Notes
https://github.com/step-security/harden-runner/security/advisories/GHSA-46g3-37rh-v698	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:stepsecurity:harden-runner:*:*:*:*:community:*:*:*

History

No history.

Information

Published : 2026-03-20 05:16

Updated : 2026-03-24 12:33

NVD link : CVE-2026-32947

Mitre link : CVE-2026-32947

CVE.ORG link : CVE-2026-32947

JSON object : View

Products Affected

stepsecurity

harden-runner

CWE

CWE-693

Protection Mechanism Failure

CWE-863

Incorrect Authorization

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