Vulnerability · Published Jun 26, 2026 · Assigned by GitHub_M

CVE-2026-52781OpenProject: Stored XSS on openproject.example.com through /api/v3/projects/{project}/work_packages via POST parameter "description"

Medium 6.4

In plain English

A medium-severity cross-site scripting in openproject from opf. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 17% of all known vulnerabilities).

Severity (CVSS 3.1)6.4Medium

Exploit odds (30 days)0.3%top 83.4% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

OpenProject is open-source, web-based project management software. Prior to 17.3.3 and 17.4.1, the HTML sanitizer grants <macro> elements unrestricted data-* attributes via :data wildcard. An attacker injects data-controller="poll-for-changes" into a work package description, causing Stimulus.js to mount a controller that fetches an attacker-uploaded attachment and passes it to renderStreamMessage(). This executes arbitrary Turbo Stream actions — including redirect_to — in every victim's authenticated browser session, redirecting them to an attacker-controlled server. This vulnerability is fixed in 17.3.3 and 17.4.1.

Affected products (as reported)

Vendor	Product	Versions
opf	openproject	< 17.3.3>= 17.4.0, < 17.4.1

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

References

https://github.com/opf/openproject/security/advisories/GHSA-q33w-f822-hg8x x_refsource_CONFIRM