CVE-2026-32946
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- High
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
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.
- Record
CVE-2026-32946- CVSS 4.0
- 4.6 Medium
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 - Weakness
- CWE-693, CWE-863
- Updated
- 2026-11-02
EUVDEUVD-2026-13517
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.
- Record
EUVD-2026-13517- CVSS 4.0
- 4.6 Medium
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-g699-3x6g-wm3g
Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)
Summary
A vulnerability exists in the Community Tier of Harden-Runner that allows bypassing the egress-policy: block network restriction using DNS queries over TCP.
Harden-Runner enforces egress policies 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 Enterprise Tier of Harden-Runner is not affected by this vulnerability.
Impact
When Harden-Runner is configured with egress-policy: block and a restrictive allowed-endpoints list, an attacker with existing code execution capabilities within a GitHub Actions workflow can bypass the egress block policy by initiating DNS queries over TCP to external resolvers. This allows outbound network communication that evades the configured network restrictions.
This vulnerability affects only the Community Tier. It requires the attacker to already have code execution capabilities within the GitHub Actions workflow.
Remediation
For Community Tier Users
Upgrade to Harden-Runner v2.16.0 or later.
For Enterprise Tier Users
No action required. Enterprise tier customers are not affected by this vulnerability.
Credit
We would like to thank Devansh Batham for responsibly disclosing this vulnerability through our security reporting process.
- Record
GHSA-g699-3x6g-wm3g- CVSS 4.0
- 4.6 Medium
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 - Weakness
- CWE-693, CWE-863
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-32946- CVSS 4.0
- 4.6 Medium
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 2.7 Low
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N - Weakness
- CWE-693, CWE-863
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2026-32946- CVSS 4.0
- 4.6 Medium
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 - Weakness
- CWE-693, CWE-863
- Updated
- 2026-11-02
OSVGHSA-g699-3x6g-wm3g
Egress Policy Bypass via DNS over TCP in Harden-Runner (Community Tier)
Summary
A vulnerability exists in the Community Tier of Harden-Runner that allows bypassing the egress-policy: block network restriction using DNS queries over TCP.
Harden-Runner enforces egress policies 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 Enterprise Tier of Harden-Runner is not affected by this vulnerability.
Impact
When Harden-Runner is configured with egress-policy: block and a restrictive allowed-endpoints list, an attacker with existing code execution capabilities within a GitHub Actions workflow can bypass the egress block policy by initiating DNS queries over TCP to external resolvers. This allows outbound network communication that evades the configured network restrictions.
This vulnerability affects only the Community Tier. It requires the attacker to already have code execution capabilities within the GitHub Actions workflow.
Remediation
For Community Tier Users
Upgrade to Harden-Runner v2.16.0 or later.
For Enterprise Tier Users
No action required. Enterprise tier customers are not affected by this vulnerability.
Credit
We would like to thank Devansh Batham for responsibly disclosing this vulnerability through our security reporting process.
- Record
GHSA-g699-3x6g-wm3g- CVSS 4.0
- 4.6 Medium
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 - Weakness
- CWE-693, CWE-863
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
step-security/harden-runnerGitHub Actions |
through 2.15.1 | 2.16.0 |
step-security/harden-runnerGitHub Actions |
before 2.16.0 | 2.16.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-32946 is a medium vulnerability (CVSS 4.6) in Step-security Harden-runner, published March 17, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.26%, the 18th percentile. Fixed in step-security/harden-runner 2.16.0.
References
github.com/step-security/harden-runner/security/advisories/GHSA-g699-3x6g-wm3g
nvd.nist.gov/vuln/detail/CVE-2026-32946