Stored XSS via uploadable HTML files
Published Sep 23, 2026 · Updated Sep 23, 2026
Stored cross-site scripting in SEMCMS 4.0 through 4.2 allows remote attackers to execute script in visitors' browsers via an uploaded file. The KindEditor /Edit/php/upload_json.php handler accepts an imgFile whose .htm or .html extension is allowed, stores it under the site, and returns a reachable URL without neutralizing embedded script. Exploitation requires uploading crafted HTML and inducing a user to visit the stored file; script then runs in the site's origin with that visitor's browser privileges.
Summary
What happened
Stored cross-site scripting in SEMCMS 4.0 through 4.2 allows remote attackers to execute script in visitors' browsers via an uploaded file. The KindEditor /Edit/php/upload_json.php handler accepts an imgFile whose .htm or .html extension is allowed, stores it under the site, and returns a reachable URL without neutralizing embedded script. Exploitation requires uploading crafted HTML and inducing a user to visit the stored file; script then runs in the site's origin with that visitor's browser privileges.
The record
- CVE
- CVE-2026-96739
- Published
- Sep 23, 2026
- Updated
- Sep 23, 2026
- Vendor
- Sem-CMS
- Product
- SEMCMS
- Classifications
- T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 23, 2026CVE publishedPublication date reported by the CVE source.
- Sep 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.0
- Affected versionversion=4.1
- Affected versionversion=4.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
Public exploit references
- SEMCMS KindEditor HTML upload proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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