CVE-2026-68899 Wekan: File Upload MIME Type Validation Bypass — Stored XSS via Missing System Binary Fallback
Authenticated users can bypass MIME validation to store malicious HTML, leading to stored XSS and potential account takeover in Wekan deployments lacking the file binary.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-68899?
CVE-2026-68899 is a high-severity cross-site scripting vulnerability in wekan, published on 19 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Wekan is open source kanban built with Meteor. Prior to 9.90, isFileValid() in models/fileValidation.js used the Unix file command for content-based MIME detection, but detectMimeFromFile() silently returned undefined when that binary was unavailable and the validation fell back to the attacker-controlled fileObj.type supplied through server/routes/attachmentApi.js. On deployments with WITH_API=true and no file binary, an authenticated board member could label HTML containing JavaScript as image/png, bypass the dangerous MIME check, and store active content under the Wekan origin for execution when another user opened it. Version 9.90 adds looksLikeDangerousMarkup() to inspect file bytes and force dangerous-content scanning when MIME detection is unavailable. This issue is fixed in version 9.90.
Weakness: CWE-434
Which versions are affected by CVE-2026-68899?
How do I fix CVE-2026-68899?
No fix has been published for CVE-2026-68899 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-68899 being exploited?
There is no known exploitation of CVE-2026-68899 in the wild and no public exploit code.
Sources
Also known as GHSA-jhph-whx8-wq6p.