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Docmost CVE-2026-40927

| EUVDEUVD-2026-24487 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-04-21 GitHub_M
5.4
CVSS 3.1 · GitHub Advisory
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Severity by source

GitHub Advisory PRIMARY
5.4 MEDIUM
AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
vuln.today AI
5.4 MEDIUM

Authenticated commenter required (PR:L), victim must click link (UI:R), XSS crosses into victim session scope (S:C); no availability impact applies.

3.1 AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

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

Lifecycle Timeline

5
Analysis Generated
Jul 24, 2026 - 05:36 vuln.today
Patch released
Apr 23, 2026 - 15:50 nvd
Patch available
Patch available
Apr 21, 2026 - 22:17 EUVD
EUVD ID Assigned
Apr 21, 2026 - 21:01 euvd
EUVD-2026-24487
CVE Published
Apr 21, 2026 - 20:52 nvd
MEDIUM 5.4

DescriptionGitHub Advisory

Docmost is open-source collaborative wiki and documentation software. Prior to 0.80.0, when leaving a comment on a page, it is possible to include a JavaScript URI as the link. When a user clicks on the link the JavaScript executes. This vulnerability is fixed in 0.80.0.

AnalysisAI

Stored cross-site scripting in Docmost's comment system allows authenticated users to plant javascript: URI hyperlinks that execute arbitrary JavaScript when victims click them. All Docmost instances prior to version 0.80.0 are affected (CPE: cpe:2.3:a:docmost:docmost:*). No active exploitation has been confirmed - SSVC exploitation status is 'none' and the vulnerability is absent from CISA KEV - and EPSS at 0.03% (8th percentile) indicates minimal real-world exploitation probability. Vendor-released patch is available in version 0.80.0.

Technical ContextAI

Docmost is an open-source collaborative wiki and documentation platform. The flaw is rooted in CWE-79 (Improper Neutralization of Input During Web Page Generation - Cross-Site Scripting): when a user inserts a hyperlink into a comment, Docmost fails to validate or sanitize the URL scheme, permitting the javascript: URI to pass through to rendered HTML. When a victim user clicks the link, the browser executes the embedded JavaScript within Docmost's origin context, inheriting that origin's session cookies and storage. The CVSS S:C (Changed Scope) metric confirms the payload crosses trust boundaries from the comment author's context to the victim's active session, a defining characteristic of stored XSS exploited via user-clickable links.

RemediationAI

Upgrade Docmost to version 0.80.0 or later, the vendor-confirmed fixed release per advisory GHSA-4gv6-jw3v-wc34 at https://github.com/docmost/docmost/security/advisories/GHSA-4gv6-jw3v-wc34. If immediate upgrade is not feasible, restrict commenting permissions to only explicitly trusted and authenticated users, reducing the pool of potential attackers - note this trades collaboration functionality for security posture. Deploying a Content Security Policy (CSP) header that includes 'script-src' without 'unsafe-inline' and explicitly blocks javascript: URI navigation (via 'default-src' or 'navigate-to' directives) can mitigate execution of injected payloads in modern browsers; however, CSP effectiveness depends on correct web server or reverse-proxy configuration and requires testing against Docmost's frontend to avoid breaking legitimate functionality.

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CVE-2026-40927 vulnerability details – vuln.today

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