CVE-2026-25598VulnerabilityPublished 9 Feb 2026

CVE-2026-25598: step-security harden-runner · Insufficient Logging

Affects step-security harden-runnerSource CVE Database V5

Not known to be exploited · CVSS 6.3 Medium : upgrade to 2.14.2 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

6.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.14.2

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 9 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade step-security harden-runner to 2.14.2.

Affected software

Product	Affected	Fixed in
step-securityharden-runner	Affected <2.14.2	Fixed in 2.14.2

AI-suggested

European organizations should immediately upgrade Harden-Runner to version 2.14.2 or later to ensure comprehensive audit logging of all outbound network traffic, including traffic using sendto, sendmsg, and sendmmsg socket calls. In addition to patching, organizations should: 1) Review and tighten egress policies in CI/CD environments to restrict unnecessary outbound connections. 2) Implement network-level monitoring and logging to complement Harden-Runner’s capabilities, such as using network intrusion detection systems (NIDS) or egress firewalls that can detect anomalous UDP or multi-message traffic. 3) Conduct regular audits of CI/CD runner configurations and logs to identify gaps or suspicious activity. 4) Employ anomaly detection tools that analyze network traffic patterns for unusual behavior that might bypass application-level logging. 5) Educate DevOps and security teams about this vulnerability and the importance of layered monitoring. 6) Integrate Harden-Runner logs with centralized Security Information and Event Management (SIEM) systems for correlation and alerting. These steps will help mitigate the risk of stealthy data exfiltration or command-and-control communication attempts.

Description

CVE-2026-25598 is a medium-severity vulnerability in the step-security Harden-Runner GitHub Action prior to version 2.14.2. It allows outbound network connections made via certain socket system calls (sendto, sendmsg, sendmmsg) to evade audit logging when egress-policy is set to audit. This insufficient logging weakness (CWE-778) can undermine the visibility of potentially malicious outbound traffic in CI/CD environments using Harden-Runner. The vulnerability does not require authentication or user interaction and has a CVSS score of 6.3. It is fixed in version 2.14.2.

Impact

For European organizations, especially those relying on GitHub Actions for CI/CD pipelines and employing Harden-Runner for security monitoring, this vulnerability can significantly reduce visibility into outbound network traffic. This lack of audit logging can allow attackers to stealthily exfiltrate sensitive intellectual property, credentials, or configuration data, or maintain covert command-and-control channels. The impact is particularly critical for sectors with stringent compliance and data protection requirements, such as finance, healthcare, and critical infrastructure. Reduced logging undermines incident detection and forensic investigations, increasing the risk of prolonged undetected breaches. Additionally, organizations may face regulatory consequences if audit trails are incomplete, violating GDPR or other local data protection laws. While the vulnerability does not directly compromise system integrity or availability, the diminished monitoring capability can facilitate more severe downstream attacks.

CWE-778Insufficient Logging (opens in a new tab)
Base weaknessLikelihood of exploit: MediumOWASP Top 10 A09:2025: Security Logging & Alerting Failures (opens in a new tab)
When a security-critical event occurs, the product either does not record the event or omits important details about the event when logging it.
Architecture and Design
Use a centralized logging mechanism that supports multiple levels of detail.
Implementation
Ensure that all security-related successes and failures can be logged. When storing data in the cloud (e.g., AWS S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to enable and capture detailed logging information.
Operation
Be sure to set the level of logging appropriately in a production environment. Sufficient data should be logged to enable system administrators to detect attacks, diagnose errors, and recover from attacks.
OWASP Cheat Sheets
Application Logging Vocabulary (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V7.1.3 (opens in a new tab)
V7.2.1 (opens in a new tab)
V7.1.4 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 17 Feb 2026, 09:46 UTC

WeaknessesCWE-778

Technical details

References

Community reviews

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