| Name | CVE-2026-34478 |
| 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. Two distinct issues affect users of stream-based syslog services who configure Rfc5424Layout directly: * 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. * 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. Users of the SyslogAppender are not affected, as its configuration attributes were not modified. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| apache-log4j1.2 (PTS) | bullseye | 1.2.17-10+deb11u1 | fixed |
| forky, sid, bookworm, trixie | 1.2.17-11 | fixed | |
| apache-log4j2 (PTS) | bullseye | 2.17.1-1~deb11u1 | fixed |
| bullseye (security) | 2.17.1-1~deb11u2 | fixed | |
| forky, sid, bookworm, trixie | 2.19.0-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| apache-log4j1.2 | source | (unstable) | (not affected) | |||
| apache-log4j2 | source | (unstable) | (not affected) |
- apache-log4j2 <not-affected> (Vulnerable code not present)
- apache-log4j1.2 <not-affected> (Vulnerable code not present)
https://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjvb5gwt
https://logging.apache.org/security.html#CVE-2026-34478
https://github.com/apache/logging-log4j2/pull/4074
Fixed by: https://github.com/apache/logging-log4j2/commit/6c8cf594fe853e4cf8d5180d247f8b7bc910696d (rel/2.25.4)