How severe is CVE-2026-21631?

CVE-2026-21631 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-21631 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21631?

CVE-2026-21631 affects Joomla Joomla!. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21631?

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

Does CVE-2026-21631 have an EU (EUVD) identifier?

Yes. CVE-2026-21631 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17857.

When was CVE-2026-21631 published?

CVE-2026-21631 was published on 2026-04-01 and last updated on 2026-06-17.

CVE-2026-21631

CVE-2026-21631 is a medium-severity vulnerability in Joomla Joomla! with a CVSS 3.x base score of 5.4. 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 5.4)
CVSS v4: 5.9
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-17857
Weakness: CWE-79
Affected product: Joomla Joomla!
Published: 2026-04-01
Last modified: 2026-06-17

Description

Lack of output escaping leads to a XSS vector in the multilingual associations component.

Frequently asked questions

What is CVE-2026-21631?: Lack of output escaping leads to a XSS vector in the multilingual associations component.
How severe is CVE-2026-21631?: CVE-2026-21631 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-21631 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21631?: CVE-2026-21631 affects Joomla Joomla!. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21631?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21631 have an EU (EUVD) identifier?: Yes. CVE-2026-21631 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-17857.
When was CVE-2026-21631 published?: CVE-2026-21631 was published on 2026-04-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:joomla:joomla\!:*:*:*:*:*:*:*:*

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