How severe is CVE-2026-39840?

CVE-2026-39840 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-2026-39840 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-39840?

CVE-2026-39840 affects Mediawiki Cargo. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-39840?

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

Does CVE-2026-39840 have an EU (EUVD) identifier?

Yes. CVE-2026-39840 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19929.

When was CVE-2026-39840 published?

CVE-2026-39840 was published on 2026-04-07 and last updated on 2026-06-17.

CVE-2026-39840

CVE-2026-39840 is a medium-severity vulnerability in Mediawiki Cargo 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 v4: 5.1
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-19929
Weakness: CWE-79
Affected product: Mediawiki Cargo
Published: 2026-04-07
Last modified: 2026-06-17

Description

Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Wikimedia Foundation Mediawiki - Cargo Extension allows XSS Targeting Non-Script Elements.This issue affects Mediawiki - Cargo Extension: before 3.8.7.

Frequently asked questions

What is CVE-2026-39840?: Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Wikimedia Foundation Mediawiki - Cargo Extension allows XSS Targeting Non-Script Elements.This issue affects Mediawiki - Cargo Extension: before 3.8.7.
How severe is CVE-2026-39840?: CVE-2026-39840 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-2026-39840 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-39840?: CVE-2026-39840 affects Mediawiki Cargo. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-39840?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-39840 have an EU (EUVD) identifier?: Yes. CVE-2026-39840 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-19929.
When was CVE-2026-39840 published?: CVE-2026-39840 was published on 2026-04-07 and last updated on 2026-06-17.

References

Affected products (1)

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

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