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🛡️ CVE-2026-32946 — harden-runner

🟢 CVSS 2.7 — Low ✅ No Known Exploit CWE-693 NVD
2.7
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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](https://github.com/devanshbatham) for responsibly disclosing this vulnerability through our security reporting process.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity none, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: High — administrative rights are needed first.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: None.
  • Availability impact: None.

Weakness class

CVE-2026-32946 is classified as CWE-693: Protection Mechanism Failure. A protection exists but does not cover the case at hand, so it can be worked around.

Affected software

CVE-2026-32946 is recorded against 2 packages.

  • harden-runner (fixed in 2.16.0)
  • step-security/harden-runner (fixed in 2.16.0)

Timeline and source

Published on 20 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com
github.com

Other advisories for this package

harden-runner has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-693: Protection Mechanism Failure) in other software:

Details

Severity LOW
CVSS Score 2.7
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
CWE CWE-693
Public Exploit ✅ No
Source NVD
Published 2026-03-20
Updated 2026-08-20
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
harden-runner — 2.16.0
step-security/harden-runner — 2.16.0

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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