Stepsecurity Harden-runner vulnerabilities
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Published CVEs affecting Stepsecurity Harden-runner: 3 record(s), with affected versions and fixes.cpe:2.3:a:stepsecurity:harden-runner
CVE-2026-32947
Medium · 4.9
CWE-693 Mar 20, 2026
Egress Policy Bypass via DNS over HTTPS (DoH) in Harden-Runner (Community Tier)
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.
CVE-2026-32946
Low · 2.7
CWE-693 Mar 20, 2026
Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)
Harden-Runner is a CI/CD security agent that works like an EDR for GitHub Actions runners. In versions 2.15.1 and below, the Harden-Runner that allows bypass of the egress-policy: block network restriction using DNS queries over TCP. Egress policies are enforced 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 issue has been fixed in version 2.16.0.
CVE-2026-25598
Medium · 5.3
CWE-778 Feb 9, 2026
Bypassing Logging of Outbound Connections Using sendto, sendmsg, and sendmmsg in Harden-Runner (Community Tier)
Harden-Runner is a CI/CD security agent that works like an EDR for GitHub Actions runners. Prior to 2.14.2, a security vulnerability has been identified in the Harden-Runner GitHub Action (Community Tier) that allows outbound network connections to evade audit logging. Specifically, outbound traffic using the sendto, sendmsg, and sendmmsg socket system calls can bypass detection and logging when using egress-policy: audit. This vulnerability is fixed in 2.14.2.