What is CVE-2020-5577?

CVE-2020-5577 is a high-severity vulnerability in Sixapart Movable Type, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2020-05-14.

How severe is CVE-2020-5577?

High severity. CVSS v3 base score is 8.8 out of 10.

Arbitrary file upload in Sixapart Movable Type

CVE-2020-5577

Movable Type series (Movable Type 7 r.4606 (7.2.1) and earlier (Movable Type 7), Movable Type Advanced 7 r.4606 (7.2.1) and earlier (Movable Type Advanced 7), Movable Type for AWS 7 r.4606 (7.2.1) and earlier (Movable Type for AWS 7), Movable Type 6.5.3 and earlier (Movable Type 6.5), Movable Type Advanced 6.5.3 and earlier (Movable Type Advanced 6.5), Movable Type 6.3.11 and earlier (Movable Type 6.3), Movable Type Advanced 6.3.11 and earlier (Movable Type 6.3), Movable Type Premium 1.29 and earlier, and Movable Type Premium Advanced 1.29 and earlier) allow remote authenticated attackers to upload arbitrary files and execute a php script via unspecified vectors.

Vulnerability class: Unrestricted File Upload

Published 2020-05-14 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.017 (76.7th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 77th percentile — 76.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000

Affected products

Sixapart Movable Type
Six Apart Ltd. Movable Type — versions Movable Type 7 r.4606 (7.2.1) and earlier (Movable Type 7), Movable Type Advanced 7 r.4606 (7.2.1) and earlier (Movable Type Advanced 7), Movable Type for AWS 7 r.4606 (7.2.1) and earlier (Movable Type for AWS 7), Movable Type 6.5.3 and earlier (Movable Type 6.5), Movable Type Advanced 6.5.3 and earlier (Movable Type Advanced 6.5), Movable Type 6.3.11 and earlier (Movable Type 6.3), Movable Type Advanced 6.3.11 and earlier (Movable Type 6.3), Movable Type Premium 1.29 and earlier, and Movable Type Premium Advanced 1.29 and earlier

Weakness classification (CWE)

CWE-434 — Unrestricted Upload of File with Dangerous Type

References

movabletype.org/news/2020/05/mt-730-660-6312-released.html (Release Notes, Vendor Advisory)
jvn.jp/en/jp/JVN28806943/index.html (VDB Entry, Third Party Advisory)

Frequently asked questions

What is CVE-2020-5577?: CVE-2020-5577 is a high-severity vulnerability in Sixapart Movable Type, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2020-05-14.
How severe is CVE-2020-5577?: High severity. CVSS v3 base score is 8.8 out of 10.