# CVE-2026-84648: Jenkins system log viewer stored XSS in metadata

Source: https://junglewise.ai/threats/cve-2026-84648-jenkins-system-log-viewer-stored-xss-in-metadata  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-02. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-84648 · Severity: high · CVSS 8.8 · Published 2026-09-02

Jenkins is an automation server widely used for continuous integration and deployment pipelines. The system log viewer in Jenkins does not properly escape log metadata (source, level, timestamp), allowing attackers who control agent processes to inject malicious scripts that execute in the browsers of administrators viewing logs. This could lead to session hijacking, credential theft, or further compromise of the Jenkins infrastructure.

Technologies: [Jenkins](https://junglewise.ai/threats/technologies/jenkins). Vendors: [Jenkins](https://junglewise.ai/threats/vendors/jenkins).

## Quick answers

**Is CVE-2026-84648 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-84648 being exploited in the wild.

**How severe is CVE-2026-84648?** High severity, with a CVSS score of 8.8, published 2 September 2026.

**Which products and versions are affected?** Jenkins 2.579 and earlier, LTS 2.568.2 and earlier.

**Is there a fix for CVE-2026-84648?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-84648 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-84648?** Check whether you run Jenkins at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a stored cross-site scripting (XSS) flaw in Jenkins' system log viewer component. The root cause is insufficient output encoding of log record metadata fields (source, level, timestamp) before rendering in HTML. Attackers with control over agent processes can inject JavaScript payloads into log records; when an administrator views the system logs, the malicious script executes in their browser context. No authentication is required beyond agent process control. The fix in Jenkins 2.580 and LTS 2.568.3 properly escapes these metadata fields. Content Security Policy (CSP) provides partial mitigation on Jenkins 2.539+ and LTS 2.541.1+.

## Affected products

- Jenkins Jenkins 2.579 and earlier, LTS 2.568.2 and earlier

## Timeline

- 2026-09-02: disclosed

## References

- [https://www.jenkins.io/security/advisory/2026-09-02/](https://www.jenkins.io/security/advisory/2026-09-02/)

## Related threats

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- [Jenkins missing HTTP proxy permission check](https://junglewise.ai/threats/cve-2026-117625-a-missing-permission-check-in-jenkins-2-587-and-earlier-lts-2)
- [Jenkins deserialization filter bypass in XStream resolves-to attribute](https://junglewise.ai/threats/cve-2026-117624-jenkins-2-587-and-earlier-lts-2-580-1-and-earlier-does-not)
- [Jenkins stored cross-site scripting in breadcrumb menu tooltips](https://junglewise.ai/threats/cve-2026-117623-jenkins-2-587-and-earlier-lts-2-580-1-and-earlier-does-not)
- [Jenkins agent XSS via Stapler HttpResponse exceptions](https://junglewise.ai/threats/cve-2026-117622-jenkins-2-587-and-earlier-lts-2-580-1-and-earlier-allows-agents)