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.
Configurations

Configuration 1 (hide)

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

History

24 Mar 2026, 12:33

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : unknown
v3 : 4.9
CPE cpe:2.3:a:stepsecurity:harden-runner:*:*:*:*:community:*:*:*
First Time Stepsecurity harden-runner
Stepsecurity
Summary
  • (es) Harden-Runner es un agente de seguridad de CI/CD que funciona como un EDR para los runners de GitHub Actions. En las versiones 2.15.1 e inferiores, una vulnerabilidad de DNS sobre HTTPS (DoH) permite a los atacantes eludir las restricciones de red de 'egress-policy: block' al tunelizar datos exfiltrados a través de puntos finales HTTPS permitidos como dns.google. El ataque funciona codificando datos sensibles (por ejemplo, el nombre de host del runner) como subdominios en consultas DoH, que aparecen como tráfico HTTPS legítimo para el filtrado basado en dominio de Harden-Runner pero que finalmente se reenvían a un dominio controlado por el atacante. Esto permite eficazmente la exfiltración de datos sin conectarse directamente a ningún destino bloqueado. La explotación requiere que el atacante ya tenga ejecución de código dentro del flujo de trabajo de GitHub Actions. El problema se solucionó en la versión 2.16.0.
References () https://github.com/step-security/harden-runner/releases/tag/v2.16.0 - () https://github.com/step-security/harden-runner/releases/tag/v2.16.0 - Product, Release Notes
References () https://github.com/step-security/harden-runner/security/advisories/GHSA-46g3-37rh-v698 - () https://github.com/step-security/harden-runner/security/advisories/GHSA-46g3-37rh-v698 - Vendor Advisory

20 Mar 2026, 05:16

Type Values Removed Values Added
New CVE

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