What’s Vulnerable › Vulnerabilities

CVE-2020-8421

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.0% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-01-28 · updated 2026-06-17
• Weakness: CWE-79

Description

An issue was discovered in Joomla! before 3.9.15. Inadequate escaping of usernames allows XSS attacks in com_actionlogs.

Affected products

• Joomla!: from 3.9.0 before 3.9.14 — fixed in 3.9.14

How to fix

Upgrade to a fixed version: Joomla! 3.9.14. Check the vendor advisory for mitigations.

References

• https://developer.joomla.org/security-centre/800-20200103-core-xss-in-com-actionlogs
• https://developer.joomla.org/security-centre/800-20200103-core-xss-in-com-actionlogs

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