Browser script execution via stored comment input
Published Feb 4, 2026 · Updated Feb 4, 2026
Stored XSS in affected Six Apart Ltd. Movable Type releases allows remote authenticated users to run script in a logged-in user's browser. Six Apart identifies the Edit Comment and theme-listing screens but has not disclosed which field or rendering operation fails to neutralize stored input. Low-privileged access is required to store crafted content, and execution occurs only when a logged-in user opens an affected screen; the reported consequence is browser-context script execution.
Summary
What happened
Stored XSS in affected Six Apart Ltd. Movable Type releases allows remote authenticated users to run script in a logged-in user's browser. Six Apart identifies the Edit Comment and theme-listing screens but has not disclosed which field or rendering operation fails to neutralize stored input. Low-privileged access is required to store crafted content, and execution occurs only when a logged-in user opens an affected screen; the reported consequence is browser-context script execution.
The record
- CVE
- CVE-2026-21393
- Published
- Feb 4, 2026
- Updated
- Feb 4, 2026
- Vendor
- Six Apart Ltd.
- Product
- Movable Type Advanced
- Classifications
- CWE-79
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 4, 2026CVE publishedPublication date reported by the CVE source.
- Feb 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=8.0.2 to 8.0.8 (8.0 series)
- Affected versionversion=8.8.0 to 8.8.1 (8.8 series)
- Affected versionversion=9.0.4 to 9.0.5 (9.0 series)
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo