Bug 2506845

Summary: CVE-2026-66010 fbthrift: DOMPurify: Cross-Site Scripting (XSS) via custom element attribute bypass [epel-all]
Product: [Fedora] Fedora EPEL Reporter: Ganesh <gnaik>
Component: fbthriftAssignee: Michel Lind <michel>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: epel9CC: michel
Target Milestone: ---Keywords: Security, SecurityTracking
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard: {"flaws": ["6b1db381-899f-4e90-84fe-976062325d58"]}
Fixed In Version: Doc Type: ---
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2026-08-04 19:46:03 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2443016, 2487042, 2506731    

Description Ganesh 2026-07-24 16:55:14 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 3.4.12 fails to execute afterSanitizeElements hook for custom elements allowed via CUSTOM_ELEMENT_HANDLING.tagNameCheck, allowing attributes to bypass application security policies. Attackers can preserve sensitive attributes on custom elements that later re-inject them into innerHTML sinks, creating second-order XSS gadgets.
Comment 1 Michel Lind 2026-08-04 17:30:43 UTC 
Reassigning from `epel10` to `epel9`: Bug filed against a branch the package never shipped on.
Comment 2 Michel Lind 2026-08-04 19:46:03 UTC 
This CVE is in a JavaScript/NodeJS package; the JavaScript here is not shipped in the binary RPMs.