Arbitrary file upload in Six Apart Ltd. Movable Type Advanced (Software Edition)
CVE-2026-23704
A non-administrative user can upload malicious files. When an administrator or the product accesses that file, an arbitrary script may be executed on the administrator's browser. Note that Movable Type 7 series and 8.4 series, which are End-of-Life (EOL), are affected by the vulnerability as well.
Vulnerability class: Unrestricted File Upload
EPSS: 0.002 (10.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L.
Affected products
- Six Apart Ltd. Movable Type Advanced (Software Edition) — versions 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 (Cloud Edition) — versions 9.0.5 (9 series), 8.8.1 (8 series)
- Six Apart Ltd. Movable Type Premium (Advanced Edition) (Software — versions 9.0.4 (MTP 9.0 series), 2.13 and earlier (MTP 2 series)
- Six Apart Ltd. Movable Type Premium (Cloud Edition) — versions 9.0.5 (9 series), 2.12 (MTP 2 series)
- Six Apart Ltd. Movable Type Premium (Software Edition) — versions 9.0.4 (MTP 9.0 series), 2.13 and earlier (MTP 2 series)
- Six Apart Ltd. Movable Type (Software Edition) — versions 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)
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-23704?
- CVE-2026-23704 is a medium-severity vulnerability in Six Apart Ltd. Movable Type Advanced (Software Edition), classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 6.5/10. Published 2026-02-04.
- How severe is CVE-2026-23704?
- Medium severity. CVSS v3 base score is 6.5 out of 10.