step-security harden-runner up to 2.15.x protection mechanism

Summaryinfo

A vulnerability was found in step-security harden-runner up to 2.15.x and classified as problematic. Affected by this vulnerability is an unknown functionality. Such manipulation leads to protection mechanism. This vulnerability is traded as CVE-2026-32946. The attack may be launched remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in step-security harden-runner up to 2.15.x and classified as problematic. Affected by this issue is an unknown code. The manipulation with an unknown input leads to a protection mechanism vulnerability. Using CWE to declare the problem leads to CWE-693. The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. Impacted is confidentiality. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-32946 since 03/17/2026. The exploitation is known to be easy. The attack may be launched remotely. Additional levels of successful authentication are needed for exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 2.16.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

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Productinfo

Vendor

• step-security

Name

• harden-runner

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15

Website

• Product: https://github.com/step-security/harden-runner/

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