How severe is CVE-2021-42042?

CVE-2021-42042 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-42042 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-42042?

CVE-2021-42042 affects Mediawiki. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-42042?

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

When was CVE-2021-42042 published?

CVE-2021-42042 was published on 2021-10-06 and last updated on 2026-06-17.

CVE-2021-42042

CVE-2021-42042 is a medium-severity vulnerability in Mediawiki with a CVSS 3.x base score of 4.8. 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 4.8)
CVSS v2: 3.5
EPSS exploit prediction: 1% (41st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Mediawiki
Published: 2021-10-06
Last modified: 2026-06-17

Description

An issue was discovered in SpecialEditGrowthConfig in the GrowthExperiments extension in MediaWiki through 1.36.2. The growthexperiments-edit-config-error-invalid-title MediaWiki message was not being properly sanitized and allowed for the injection and execution of HTML and JavaScript.

Frequently asked questions

What is CVE-2021-42042?: An issue was discovered in SpecialEditGrowthConfig in the GrowthExperiments extension in MediaWiki through 1.36.2. The growthexperiments-edit-config-error-invalid-title MediaWiki message was not being properly sanitized and allowed for the injection and execution of HTML and JavaScript.
How severe is CVE-2021-42042?: CVE-2021-42042 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-42042 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (41st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-42042?: CVE-2021-42042 affects Mediawiki. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-42042?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-42042 published?: CVE-2021-42042 was published on 2021-10-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mediawiki:mediawiki:*:*:*:*:*:*:*:*

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