CVE-2020-8421
CVE-2020-8421 is a medium-severity vulnerability in Joomla Joomla! 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 v2: 4.3
- EPSS exploit prediction: 1% (57th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-79
- Affected product: Joomla Joomla!
- Published:
- Last modified:
Description
An issue was discovered in Joomla! before 3.9.15. Inadequate escaping of usernames allows XSS attacks in com_actionlogs.
Frequently asked questions
- What is CVE-2020-8421?
- An issue was discovered in Joomla! before 3.9.15. Inadequate escaping of usernames allows XSS attacks in com_actionlogs.
- How severe is CVE-2020-8421?
- CVE-2020-8421 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-2020-8421 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2020-8421?
- CVE-2020-8421 affects Joomla Joomla!. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2020-8421?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2020-8421 published?
- CVE-2020-8421 was published on 2020-01-28 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:joomla:joomla\!:*:*:*:*:*:*:*:*
More vulnerabilities in Joomla Joomla!
- CVE-2026-48904 — Critical (CVSS 9.8): An improper access check allows privelege escalation through the com_users group editing webservice endpoint.
- CVE-2026-48902 — Critical (CVSS 9.8): The password and username reset features created plain http links for https connections if the "Force SSL" flag wasn't…
- CVE-2026-48899 — Critical (CVSS 9.8): An improper access check allows privilege escalation through the com_users batch task.
- CVE-2026-48898 — Critical (CVSS 9.8): An improper access check allows privilege escalation through the com_users batch task.
- CVE-2026-40383 — Critical (CVSS 9.8): An improper validation of user-supplied input leads to a local file inclusion vulnerability.
- CVE-2026-35223 — Critical (CVSS 9.8): An improper access check allows unauthorized access to com_config webservice endpoints.
All CVEs affecting Joomla Joomla! →
Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities
- CVE-2025-49410 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Imran Emu TC…
- CVE-2024-47875 — Critical (CVSS 10.0): DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. DOMpurify was vulnerable to…
- CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
- CVE-2023-45144 — Critical (CVSS 10.0): com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on…
- CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
- CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…
Browse all CWE-79 (Cross-site Scripting (XSS)) vulnerabilities →