Bug 2520367

Summary: CVE-2026-65912 nextcloud: DOMPurify: URI validation bypass leads to cross-site scripting [fedora-all]
Product: [Fedora] Fedora Reporter: Ganesh <gnaik>
Component: nextcloudAssignee: Andrew Bauer <zonexpertconsulting>
Status: CLOSED CURRENTRELEASE QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: medium Docs Contact:
Priority: medium    
Version: rawhideCC: pampelmuse, zonexpertconsulting
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["c1e6b029-b965-4e40-bc75-032fc39ed932"]}
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Last Closed: 2026-08-20 15:15:43 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 2506427    

Description Ganesh 2026-08-20 14:53:39 UTC 
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

DOMPurify before 3.3.2 contains a URI validation bypass vulnerability when ADD_ATTR is provided as a predicate function via EXTRA_ELEMENT_HANDLING.attributeCheck. Attackers can supply a predicate that accepts specific attribute and tag combinations to bypass URI-safe validation, allowing unsafe protocols like javascript: to survive sanitization and execute as DOM-based XSS when the link is activated.
Comment 1 Andrew Bauer 2026-08-20 15:15:43 UTC 
This bug is not valid. As of this writing, the current Nextcloud 34.0.3 release contain DOMPurify 3.4.13 which does not contain this CVE.

See:
https://github.com/nextcloud/server/blob/v34.0.3/package-lock.json#L6512