{"cve":"CVE-2026-34478","nvd":{"published":"2026-04-10T16:16:31.070","modified":"2026-10-26T22:10:00.163","status":"Analyzed","description":"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-relevant configuration attributes.\n\nTwo distinct issues affect users of stream-based syslog services who configure Rfc5424Layout directly:\n\n  *  The newLineEscape attribute was silently renamed, causing newline escaping to stop working for users of TCP framing (RFC 6587), exposing them to CRLF injection in log output.\n  *  The useTlsMessageFormat attribute was silently renamed, causing users of TLS framing (RFC 5425) to be silently downgraded to unframed TCP (RFC 6587), without newline escaping.\n\n\nUsers of the SyslogAppender are not affected, as its configuration attributes were not modified.\n\nUsers are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N","score":6.9},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","score":7.5},"cwes":["CWE-117","CWE-684"],"references":["https://github.com/apache/logging-log4j2/pull/4074","https://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjvb5gwt","https://logging.apache.org/cyclonedx/vdr.xml","https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout","https://logging.apache.org/security.html#CVE-2026-34478"],"products":["apache:log4j"],"source":"nvd","synced_at":"2026-10-26T22:26:44.656832877+00:00"},"epss":{"cve":"CVE-2026-34478","score":0.00972,"percentile":0.61728,"date":"2026-10-26"},"kev":null,"osv":[{"id":"GHSA-445c-vh5m-36rj","url":"https://osv.dev/vulnerability/GHSA-445c-vh5m-36rj","summary":"Apache Log4j Core: log injection in `Rfc5424Layout` due to silent configuration incompatibility","modified":"2026-09-10T03:50:42.646598813Z","packages":[{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","purl":"pkg:maven/org.apache.logging.log4j/log4j-core","ranges":[">=2.21.0 <2.25.4"],"fixed":["2.25.4"]},{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","purl":"pkg:maven/org.apache.logging.log4j/log4j-core","ranges":[">=3.0.0-beta1 <=3.0.0-beta3"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}