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CVE-2026-32946— Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)

Quick assessment

Affected
step-security harden-runner
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Harden-Runner是StepSecurity开源的一个程序。为 GitHub 托管和自托管的跑步者提供网络出口过滤和运行时安全。 Harden-Runner 2.15.1及之前版本存在安全漏洞，该漏洞源于允许通过TCP进行DNS查询绕过出口策略网络限制。

AI Predicted 4.9 Difficulty: Easy EPSS 0.39% · P31

Possible ATT&CK Techniques 1 AI

T1071.004 · DNS
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I. Basic Information for CVE-2026-32946

Vulnerability Information
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Vulnerability Title
Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
保护机制失效
Source: CVE Program / CVE List V5
Vulnerability Title
Harden-Runner 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Harden-Runner是StepSecurity开源的一个程序。为 GitHub 托管和自托管的跑步者提供网络出口过滤和运行时安全。 Harden-Runner 2.15.1及之前版本存在安全漏洞，该漏洞源于允许通过TCP进行DNS查询绕过出口策略网络限制。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
step-security harden-runner < 2.16.0 -

II. Public POCs for CVE-2026-32946

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III. Intelligence Information for CVE-2026-32946

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Patches & Fixes for CVE-2026-32946 (1)

Vendor Advisories for CVE-2026-32946 (1)

IV. Related Vulnerabilities

Same product: harden-runner
Same vendor: step-security
Same weakness: CWE-693

V. Comments for CVE-2026-32946

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