Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-124492 Overview
SunEditor before 3.4.0 contains a stored cross-site scripting vulnerability in ModalAnchorEditor's #createBookmarkList, which inserts entity-decoded h1-h6 header textContent into the bookmark list via innerHTML without escaping. Attackers can store HTML-encoded payloads in editor headers that execute JavaScript when a victim opens the link modal and types # in the URL input.
Critical Impact
Affected Products
- SunEditor: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-08: CVE-2026-124492 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-08: last updated in the NVD database
Technical Details for CVE-2026-124492
Vulnerability Analysis
CVE-2026-124492 is a Cross Site Scripting weakness (CWE-79: Cross Site Scripting) in SunEditor. Based on its CVSS vector, the flaw can be reached over the network, needs some level of access, and relies on a user taking an action. Attacker supplied script runs in another user's browser inside the trusted site.
With a CVSS base score of 8.3, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The weakness is classified as CWE-79: Cross Site Scripting. Attacker supplied script runs in another user's browser inside the trusted site.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs some level of access, and relies on a user taking an action. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Detection Methods for CVE-2026-124492
Detection Strategies
- Inventory every instance of SunEditor and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward SunEditor application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-124492
Immediate Actions Required
- Apply the fixed version of SunEditor named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for SunEditor.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
- CWE-79: Cross Site Scripting More CVEs with this weakness
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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