Vulnerability in Apache Log4j
CVE-2026-34480
Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#cha…
EPSS: 0.009 (54.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
Affected products
- Apache Log4j — versions 3.0.0
- Apache Software Foundation Log4j Core — versions 2.0-alpha1, 3.0.0-alpha1
Weakness classification (CWE)
References
- security@apache.org (Patch, patch, Issue Tracking)
- security@apache.org (vendor-advisory, Vendor Advisory)
- security@apache.org (Product, vendor-advisory)
- security@apache.org (Technical Description, related)
- security@apache.org (vendor-advisory, Mailing List, Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108 (Mailing List, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-34480?
- CVE-2026-34480 is a high-severity vulnerability in Apache Log4j, classified under Improper Encoding or Escaping of Output. CVSS score: 7.5/10. Published 2026-04-10.
- How severe is CVE-2026-34480?
- High severity. CVSS v3 base score is 7.5 out of 10.