How severe is CVE-2021-39186?

CVE-2021-39186 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2021-39186 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-2021-39186?

CVE-2021-39186 affects Miraheze Globalnewfiles. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39186?

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

When was CVE-2021-39186 published?

CVE-2021-39186 was published on 2021-09-01 and last updated on 2026-06-17.

CVE-2021-39186

CVE-2021-39186 is a medium-severity vulnerability in Miraheze Globalnewfiles with a CVSS 3.x base score of 4.3. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 4.3
EPSS exploit prediction: 1% (59th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Miraheze Globalnewfiles
Published: 2021-09-01
Last modified: 2026-06-17

Description

GlobalNewFiles is a MediaWiki extension maintained by Miraheze. Prior to commit number cee254e1b158cdb0ddbea716b1d3edc31fa4fb5d, the username column of the GlobalNewFiles special page is vulnerable to a stored XSS. Commit number cee254e1b158cdb0ddbea716b1d3edc31fa4fb5d contains a patch. As a workaround, one may disallow <,> (or other characters required to insert html/js) from being used in account names so an XSS is not possible.

Frequently asked questions

What is CVE-2021-39186?: GlobalNewFiles is a MediaWiki extension maintained by Miraheze. Prior to commit number cee254e1b158cdb0ddbea716b1d3edc31fa4fb5d, the username column of the GlobalNewFiles special page is vulnerable to a stored XSS. Commit number cee254e1b158cdb0ddbea716b1d3edc31fa4fb5d contains a patch. As a workaround, one may disallow <,> (or other characters required to insert html/js) from being used in account names so an XSS is not possible.
How severe is CVE-2021-39186?: CVE-2021-39186 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2021-39186 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-2021-39186?: CVE-2021-39186 affects Miraheze Globalnewfiles. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39186?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39186 published?: CVE-2021-39186 was published on 2021-09-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:miraheze:globalnewfiles:*:*:*:*:*:mediawiki:*:*

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