Vulnerability in Apache Log4j
CVE-2026-34478
Apache Log4j Core's Rfc5424Layout https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout , in versions 2.21.0 through 2.25.3, is vulnerable to log injection via CRLF sequences due to undocumented renames of security-releva…
EPSS: 0.008 (53.5th 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 2.21.0, 3.0.0-beta1
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-2026-34478?
- CVE-2026-34478 is a high-severity vulnerability in Apache Log4j, classified under Improper Output Neutralization for Logs. CVSS score: 7.5/10. Published 2026-04-10.
- How severe is CVE-2026-34478?
- High severity. CVSS v3 base score is 7.5 out of 10.