How severe is CVE-2021-20814?

CVE-2021-20814 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-20814 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20814?

CVE-2021-20814 primarily affects Sixapart Movable Type. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20814?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-20814 published?

CVE-2021-20814 was published on 2021-08-26 and last updated on 2026-06-17.

CVE-2021-20814

CVE-2021-20814 is a medium-severity vulnerability in Sixapart Movable Type with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Sixapart Movable Type
Published: 2021-08-26
Last modified: 2026-06-17

Description

Cross-site scripting vulnerability in Setting screen of ContentType Information Widget Plugin of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series), Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series), and Movable Type Premium 1.44 and earlier) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.

Frequently asked questions

What is CVE-2021-20814?: Cross-site scripting vulnerability in Setting screen of ContentType Information Widget Plugin of Movable Type (Movable Type 7 r.4903 and earlier (Movable Type 7 Series), Movable Type Advanced 7 r.4903 and earlier (Movable Type Advanced 7 Series), and Movable Type Premium 1.44 and earlier) allows remote attackers to inject arbitrary script or HTML via unspecified vectors.
How severe is CVE-2021-20814?: CVE-2021-20814 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-20814 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (59th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20814?: CVE-2021-20814 primarily affects Sixapart Movable Type. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20814?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20814 published?: CVE-2021-20814 was published on 2021-08-26 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:sixapart:movable_type:*:*:*:*:premium:*:*:*
cpe:2.3:a:sixapart:movable_type:*:*:*:*:-:*:*:*
cpe:2.3:a:sixapart:movable_type:*:*:*:*:advanced:*:*:*

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