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Fencer Vulns
critical 9.8

CVE-2021-20837 in the critical feed json

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…

published 2021-10-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-8249

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
88.1%
EPSS 88.1% chance of exploitation in 30 days, percentile 99.7%
public exploits
1
Exploit-DB, plus a Nuclei check

Summary

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.

Timeline

  1. Published
  2. First public exploit (EDB-50464)

Exploit prediction

88.14% chance of exploitation in the next 30 days, higher than 99.7% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • EDB-50464 Movable Type 7 r.5002 - XMLRPC API OS Command Injection (Metasploit) webapps, 2021-10-29
  • Nuclei template MovableType - Remote Command Injection nuclei detection template
  • packetstormsecurity.com http://packetstormsecurity.com/files/164705/Movable-Type-7-r.5002-XMLRPC-API-Remote-Command-Injection.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • Six Apart Ltd. Movable Type

Classification

Weakness
  • CWE-78 Improper Neutralization of Special Elements used in an OS Command

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.