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Stored XSS regression on OpenProject using attachments and script-src self

High
klaustopher published GHSA-cvpq-cc56-gwxx Jan 19, 2026

Package

OpenProject

Affected versions

>= 16.3.0, <= 16.6.4

Patched versions

16.6.5, 17.0.0

Description

Impact

OpenProject versions >= 16.3.0, < 16.6.5 is affected by a stored XSS vulnerability in the Roadmap view. OpenProject’s roadmap view renders the “Related work packages” list for each version. When a version contains work packages from a different project (e.g., a subproject), the helper link_to_work_package prepends package.project.to_s to the link and returns the entire string with .html_safe. Because project names are user-controlled and no escaping happens before calling html_safe, any HTML placed in a subproject name is injected verbatim into the page.

Patches

The underlying issue is mitigated by setting a X-Content-Type-Options: nosniff header, which was in place until a refactoring move to Rails standard content-security policy, which did not properly apply this header in the new configuration since OpenProject 16.3.0.

Workarounds

If you cannot upgrade your installation, ensure that you add a X-Content-Type-Options: nosniff header in your proxying web application server.

Credits

This vulnerability was reported by users sam91281 as part of the YesWeHack.com OpenProject Bug Bounty program, sponsored by the European Commission.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

CVE ID

CVE-2026-23625

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.