# CVE-2026-44696: OpenProject stored CSS injection in markdown rendering pipeline

Source: https://junglewise.ai/threats/cve-2026-44696-openproject-stored-css-injection-in-markdown-rendering-pipeline  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-26. Updated: 2026-06-26  
License: CC BY 4.0 with a link back

CVE-2026-44696 · Severity: medium · CVSS 5.7 · Published 2026-06-26

OpenProject, a web-based project management platform, contains a vulnerability in how it handles rich text formatting. An authenticated user can inject malicious styling code into shared areas like project descriptions or comments. This could be used to create fake login screens to steal credentials from other users or silently track when and where users are viewing specific project tasks.

Technologies: [OpenProject GmbH OpenProject](https://junglewise.ai/threats/technologies/openproject). Vendors: [OpenProject GmbH](https://junglewise.ai/threats/vendors/openproject-gmbh).

## Quick answers

**Is CVE-2026-44696 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-44696 being exploited in the wild.

**How severe is CVE-2026-44696?** Medium severity, with a CVSS score of 5.7, published 26 June 2026.

**Which products and versions are affected?** OpenProject GmbH OpenProject < 17.4.0.

**Is there a fix for CVE-2026-44696?** 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-2026-44696 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-44696?** Check whether you run OpenProject GmbH OpenProject 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

A stored CSS injection vulnerability exists in OpenProject prior to version 17.4.0. The markdown rendering pipeline in 'sanitization_filter.rb' utilizes 'Sanitize::Config::RELAXED[:css]', which permits nearly all CSS properties within style attributes on specific HTML elements (figure, img, table, th, tr, td). An authenticated attacker with write access to formattable fields—such as work package descriptions, comments, or news—can inject malicious CSS. This can be leveraged to create full-screen phishing overlays using 'position:fixed' and 'z-index', or to exfiltrate user metadata (IP, User-Agent) via 'background-image:url()' callbacks. The vulnerability is resolved by implementing a strict whitelist of allowed CSS properties.

## Affected products

- OpenProject OpenProject < 17.4.0

## Timeline

- 2026-05-13: advisory: GitHub Security Advisory published by vendor
- 2026-06-26: disclosed: NVD publication date

## References

- [https://github.com/opf/openproject/security/advisories/GHSA-j9q2-49mp-hmq5](https://github.com/opf/openproject/security/advisories/GHSA-j9q2-49mp-hmq5)

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