CVE-2026-68899

Wekan: File Upload MIME Type Validation Bypass — Stored XSS via Missing System Binary Fallback

HIGH
8.7
CVSS Score
Published: August 19, 2026 at 07:26 PM UTC
Updated: October 26, 2026 at 10:10 AM UTC
1 product affected across 1 vendorWekan

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Severity
HIGH8.7
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 9.90
Affected range stops below 9.90, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.7HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-434

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