RCE in Sixapart Movable Type
CVE-2021-20837
Movable Type 7 r.5002 and earlier (Movable Type 7 Series), Movable Type 6.8.2 and earlier (Movable Type 6 Series), Movable Type Advanced 7 r.5002 and earlier (Movable Type Advanced 7 Series), Movable Type Advanced 6.8.2 and earlier (Movable Type Advanced 6 Series), Movable Type Premium 1.46 and earlier, and Movable Type Premium Advanced 1.46 and earlier allow remote attackers to execute arbitrary OS commands via unspecified vectors. Note that all versions of Movable Type 4.0 or later including unsupported (End-of-Life, EOL) versions are also affected by this vulnerability.
Vulnerability class: Command Injection (OS Command Injection)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.881 (99.8th percentile), scored .
High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.881 · newest: 0.881 · change: 0.000
Affected products
- Sixapart Movable Type
- Six Apart Ltd. Movable Type — versions Movable Type 7 r.5002 and earlier (Movable Type 7 Series), Movable Type 6.8.2 and earlier (Movable Type 6 Series), Movable Type Advanced 7 r.5002 and earlier (Movable Type Advanced 7 Series), Movable Type Advanced 6.8.2 and earlier (Movable Type Advanced 6 Series), Movable Type Premium 1.46 and earlier, and Movable Type Premium Advanced 1.46 and earlier
Weakness classification (CWE)
Public proof-of-concept exploits
References
- movabletype.org/news/2021/10/mt-782-683-released.html (Release Notes, Vendor Advisory)
- jvn.jp/en/jp/JVN41119755/index.html (Third Party Advisory)
- packetstormsecurity.com/files/164705/Movable-Type-7-r.5002-XMLRPC-API-Remote-Co… (Exploit, VDB Entry, Third Party Advisory)
- packetstormsecurity.com/files/164818/Movable-Type-7-r.5002-XMLRPC-API-Remote-Co… (VDB Entry, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-20837?
- CVE-2021-20837 is a critical-severity vulnerability in Sixapart Movable Type, classified under OS Command Injection. CVSS score: 9.8/10. Published 2021-10-26.
- How severe is CVE-2021-20837?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2021-20837 known to be exploited?
- 28 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.