CVE-2026-25598 Bypassing Logging of Outbound Connections Using sendto, sendmsg, and sendmmsg in Harden-Runner (Community Tier)
Attackers can bypass outbound connection logging in Harden-Runner by using specific socket calls, evading audit trails in CI/CD environments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-25598?
CVE-2026-25598 is a medium-severity vulnerability in step-security harden-runner, published on 9 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-778
Which versions are affected by CVE-2026-25598?
1 open source package ship an affected version, including step-security/harden-runner. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
step-security/harden-runner GitHub Actions | All versions | 2.14.2 |
Products include Stepsecurity Harden-Runner.
How do I fix CVE-2026-25598?
Upgrade step-security/harden-runner to 2.14.2 or later.
Is CVE-2026-25598 being exploited?
There is no known exploitation of CVE-2026-25598 in the wild and no public exploit code.
Other vulnerabilities in step-security harden-runner
Sources
Also known as GHSA-cpmj-h4f6-r6pq.