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Cross-site Scripting (XSS)Weakness · CWE-79

CVE-2026-52781

MEDIUM · 6.4 CVSS v3.1 Published 2026-06-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
70/100
Remediation priority · Elevated
Remotely reachable Zero-click 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

OpenProject's HTML sanitizer misconfiguration allows data-controller attributes on macro elements, enabling Stimulus.js to execute arbitrary Turbo Stream actions including unauthorized redirects in authenticated user sessions.

MitigationUpgrade OpenProject to version 17.3.3 or 17.4.1 to remediate the HTML sanitizer vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm OpenProject installation
    Identify the OpenProject installation path and check for the presence of OpenProject files (e.g., look for Gemfile, config/application.rb, or the openproject gem in the Gemfile.lock)
    Affected if OpenProject is not present on the system
  2. Determine installed OpenProject version
    Run command to check the OpenProject version - typically via 'openproject --version', from the Gemfile, or by querying the API endpoint /api/v3/api_version
    Affected if The installed version is lower than 17.3.3 or 17.4.1 (the fixed versions)
  3. Verify macro feature is accessible
    Check if the application has macro or WYSIWYG editor functionality enabled by examining configuration files in config/settings.yml or config/configuration.yml for enable_comments, enable_wysiwyg, or similar macro-related settings
    Affected if Macro or rich text editing features are enabled and accessible to users
  4. Inspect HTML sanitization configuration
    Examine the HTML sanitizer configuration file (typically in lib/open_project/textFormatting.rb or similar sanitization module) to check if data-controller attributes are explicitly allowed or stripped from macro elements
    Affected if The sanitizer permits data-controller attributes on macro elements without proper filtering
  5. Test for Turbo Stream action execution
    As an authenticated user, create or edit content containing a macro element with a data-controller attribute referencing a malicious Stimulus controller that triggers a Turbo Stream redirect action
    Affected if Arbitrary redirects can be executed through crafted data-controller attributes on macro elements

The environment is affected if OpenProject is installed with a version lower than 17.3.3 or 17.4.1, and the macro or WYSIWYG editor feature is enabled, allowing data-controller attributes to execute Turbo Stream actions.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade OpenProject to version 17.3.3 or 17.4.1 to remediate the HTML sanitizer vulnerability.

Recommended fix High confidence

17.3.3 or 17.4.1 (or later versions in those respective branches)

  1. 1. Identify current OpenProject version by checking the administration panel or running `openproject --version`
  2. 2. If running a version before 17.3.3 or 17.4.1, plan upgrade to either 17.3.3+ or 17.4.1+
  3. 3. For Docker installations: pull the new image tag (e.g., `openproject:17.3.3` or `openproject:17.4.1`) and restart the container
  4. 4. For package-based installations: run `apt-get update && apt-get install openproject` or the equivalent package manager update command
  5. 5. Verify the upgrade completed successfully and the application is operational
  6. 6. Confirm the version has been updated to 17.3.3 or higher, or 17.4.1 or higher
Caveat Review OpenProject release notes for the target version to check for any migration requirements or breaking changes between current and target version

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-52781 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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