Outbound Network Evasion in Harden-Runner GitHub Action by Step Security

CVE-2026-25598

What is CVE-2026-25598?

CVE-2026-25598 is a vulnerability identified in the Harden-Runner GitHub Action, developed by Step Security. Harden-Runner functions as a security agent for Continuous Integration and Continuous Deployment (CI/CD) processes, serving to enhance the security of GitHub Actions runners by monitoring activities and enforcing security policies. This particular vulnerability, existing in versions prior to 2.14.2, enables outbound network connections to bypass audit logging, specifically when utilizing socket system calls such as sendto, sendmsg, and sendmmsg. As a result, an organization could inadvertently expose sensitive data and operations to unauthorized access without detection or logging, significantly undermining the integrity of their security measures.

Potential impact of CVE-2026-25598

1. Data Exfiltration: The ability for outbound connections to evade audit logging poses a security threat, as malicious actors could extract sensitive data from the network undetected. This could lead to significant data breaches and compromise confidential information.

2. Undetected Malicious Activity: Organizations relying on the audit logging for security insights may be misled into believing their systems are secure. The evasion of logging mechanisms makes it difficult to trace and respond to unauthorized actions, enabling prolonged periods of malfeasance before detection occurs.

3. Regulatory Compliance Risks: Many industries are governed by strict data protection regulations that mandate comprehensive logging of network activity. The presence of this vulnerability could result in non-compliance with these regulations, leading to potential legal repercussions and penalties for organizations that fail to safeguard their systems adequately.

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