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.
No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Fri, 10 Apr 2026 18:15:00 +0000
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| Metrics |
ssvc
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Fri, 10 Apr 2026 17:30:00 +0000
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| References |
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Fri, 10 Apr 2026 16:00:00 +0000
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| 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. | |
| Title | Apache Log4j Core: Log injection in Rfc5424Layout due to silent configuration incompatibility | |
| First Time appeared |
Apache
Apache log4j |
|
| Weaknesses | CWE-117 CWE-684 |
|
| CPEs | cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Apache
Apache log4j |
|
| References |
| |
| Metrics |
cvssV4_0
|
Projects
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Status: PUBLISHED
Assigner: apache
Published:
Updated: 2026-04-10T17:50:12.484Z
Reserved: 2026-03-28T13:17:35.586Z
Link: CVE-2026-34478
Updated: 2026-04-10T16:18:17.528Z
Status : Received
Published: 2026-04-10T16:16:31.070
Modified: 2026-04-10T17:17:02.237
Link: CVE-2026-34478
No data.
OpenCVE Enrichment
No data.