Vulnerability · Published Feb 4, 2026 · Assigned by jpcert
CVE-2026-21393
Medium 5.4
In plain English
A medium-severity cross-site scripting in Movable Type Advanced (Software Edition) from Six Apart Ltd.. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities).
Severity (CVSS 3.0)5.4Medium
Exploit odds (30 days)0.2%top 85.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Movable Type contains a stored cross-site scripting vulnerability in Edit Comment. If crafted input is stored by an attacker, arbitrary script may be executed on a logged-in user's web browser. Note that Movable Type 7 series and 8.4 series, which are End-of-Life (EOL), are affected by the vulnerability as well.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Six Apart Ltd. | Movable Type (Software Edition) | 9.0.4 to 9.0.5 (9.0 series)8.8.0 to 8.8.1 (8.8 series)8.0.2 to 8.0.8 (8.0 series) |
| Six Apart Ltd. | Movable Type Advanced (Software Edition) | 9.0.4 to 9.0.5 (9.0 series)8.8.0 to 8.8.1 (8.8 series)8.0.2 to 8.0.8 (8.0 series) |
| Six Apart Ltd. | Movable Type Premium (Software Edition) | 9.0.4 (MTP 9.0 series)2.13 and earlier (MTP 2 series) |
| Six Apart Ltd. | Movable Type Premium (Advanced Edition) (Software Edition) | 9.0.4 (MTP 9.0 series)2.13 and earlier (MTP 2 series) |
| Six Apart Ltd. | Movable Type (Cloud Edition) | 9.0.5 (9 series)8.8.1 (8 series) |
| Six Apart Ltd. | Movable Type Premium (Cloud Edition) | 9.0.5 (9 series)2.12 (MTP 2 series) |
Weakness: CWE-79 · Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N