# CVE-2026-57303: Jenkins Assembla Plugin XXE in XML parser

Source: https://junglewise.ai/threats/cve-2026-57303-jenkins-assembla-plugin-xxe-in-xml-parser  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-24. Updated: 2026-06-24  
License: CC BY 4.0 with a link back

CVE-2026-57303 · Severity: high · CVSS 7.1 · Published 2026-06-24

The Jenkins Assembla Plugin, which integrates Jenkins with the Assembla development platform, contains a security flaw in how it processes data. An attacker who can control the responses from a configured Assembla server can exploit this to steal sensitive secrets from the Jenkins controller or force the server to make unauthorized requests to other internal systems. This could lead to the exposure of credentials or unauthorized access to private network resources.

Technologies: [Jenkins Project Assembla Plugin](https://junglewise.ai/threats/technologies/assembla-plugin), [org.jenkins-ci.plugins:assembla (Maven)](https://junglewise.ai/threats/technologies/org-jenkins-ci-plugins-assembla). Vendors: [Jenkins Project](https://junglewise.ai/threats/vendors/jenkins-project), [Maven](https://junglewise.ai/threats/vendors/maven).

## Quick answers

**Is CVE-2026-57303 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-57303 being exploited in the wild.

**How severe is CVE-2026-57303?** High severity, with a CVSS score of 7.1, published 24 June 2026.

**Which products and versions are affected?** Jenkins Project Assembla Plugin 1.4 and earlier; org.jenkins-ci.plugins:assembla (Maven) <= 1.4, ECOSYSTEM:introduced=0,last_affected=1.4.

**Is there a fix for CVE-2026-57303?** 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-2026-57303 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-57303?** Check whether you run Jenkins Project Assembla Plugin or org.jenkins-ci.plugins:assembla (Maven) 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 Jenkins Assembla Plugin 1.4 and earlier does not properly configure its XML parser to disable external entity resolution. This vulnerability class is XML External Entity (XXE) injection. An attacker who can control or spoof the responses from the configured Assembla server can provide a malicious XML payload. When parsed by the Jenkins controller, this payload can be used to extract local files (including secrets), or perform Server-Side Request Forgery (SSRF) to probe or attack internal network services. As of the advisory date, a specific patch version was not explicitly detailed in the provided snippet, though the vulnerability is confirmed in versions up to 1.4.

## Affected products

- Jenkins Project Assembla Plugin 1.4 and earlier

## Identifiers

- CVE-2026-57303
- GHSA-2q27-6p2h-q6r3

## Timeline

- 2026-06-24: disclosed
- 2026-06-24: advisory

## References

- [https://www.jenkins.io/security/advisory/2026-06-24/](https://www.jenkins.io/security/advisory/2026-06-24/)

## Related threats

- [Jenkins Assembla Plugin CSRF in connection endpoint](https://junglewise.ai/threats/cve-2026-57305-jenkins-assembla-plugin-csrf-in-connection-endpoint)
- [Jenkins Assembla Plugin missing permission check in connection endpoint](https://junglewise.ai/threats/cve-2026-57304-jenkins-assembla-plugin-missing-permission-check-in-connection)
- [Jenkins Assembla Plugin has Insufficiently Protected Credentials](https://junglewise.ai/threats/cve-2019-10420-jenkins-assembla-plugin-has-insufficiently-protected-credentials)