Cyber Resilience

CVE-2021-20813

Medium

Published: 26 August 2021

Published
26 August 2021
Modified
21 November 2024
KEV Added
Patch
CVSS Score v3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.0035 57.6th percentile
Risk Priority 12 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-20813 is a medium-severity Cross-site Scripting (CWE-79) vulnerability in Sixapart Movable Type. Its CVSS base score is 6.1 (Medium).

Operationally, ranked in the top 42.4% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Cross-site scripting vulnerability in Edit screen of Content Data of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series) and Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series)) allows remote attackers to inject…

more

arbitrary script or HTML via unspecified vectors.

CWE(s)

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

sixapart
movable type
7.0 — 7.8.0 · 7.0 — 7.8.0

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

addresses: CWE-79

Penetration testing submits XSS payloads to web applications, detecting cross-site scripting flaws for subsequent remediation.

addresses: CWE-79

Validates web inputs to reject script-related content that could produce XSS.

addresses: CWE-79

Output validation against expected content can reject or sanitize script content in generated web pages, reducing XSS exploitability.

References