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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-68899
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-19 20:17:21 UTC
Updated2026-08-21 22:16:43 UTC
DescriptionWekan 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.

Risk And Classification

Primary CVSS: v3.1 8.7 HIGH from [email protected]

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

EPSS: 0.004030000 probability, percentile 0.338710000 (date 2026-08-21)

Problem Types: CWE-434 | CWE-434 CWE-434: Unrestricted Upload of File with Dangerous Type

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary8.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
3.1CNADECLARED8.7HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
None

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Wekan Wekan affected < 9.90 Not specified

References

ReferenceSourceLinkTags
github.com/wekan/wekan/security/advisories/GHSA-jhph-whx8-wq6p [email protected] github.com
github.com/wekan/wekan/commit/f6ba472f6738bcd3763f133d3d9970f216df2263 [email protected] github.com
github.com/wekan/wekan/releases/tag/v9.90 [email protected] github.com
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