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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache Software Foundation | Apache Log4j Core | 2.21.0 – < 2.25.4, 3.0.0-beta1 – ≤ 3.0.0-beta3 | 2.25.4 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 26.04 LTS | apache-log4j1.2 | No fix yet | — |
| Ubuntu 25.10 | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 24.04 LTS | apache-log4j1.2 | No fix yet | — |
| Ubuntu 22.04 LTS | apache-log4j1.2 | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | apache-log4j1.2 | No fix yet | — |
| Ubuntu 18.04 LTS | apache-log4j1.2 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | apache-log4j2 +1 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | apache-log4j1.2 | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | airflow-3 | 3.2.1-r1 | — |
| Wolfi rolling | akhq | 0.27.0-r2 | — |
| Wolfi rolling | apache-activemq-artemis | 2.53.0-r5 | — |
| Wolfi rolling | apache-pulsar-4.2 | 4.2.1-r0 | — |
| Wolfi rolling | celeborn-0.6 | 0.6.3-r7 | — |
| Wolfi rolling | flink-2.1 | 2.1.3-r1 | — |
| Wolfi rolling | infinispan-16.1 | 16.1.3-r4 | — |
| Wolfi rolling | kafka-4.1 | 4.1.2-r2 | — |
| Wolfi rolling | kafka-4.2 | 4.2.0-r5 | — |
| Wolfi rolling | kserve-modelmesh | 0.12.0-r31 | — |
| Wolfi rolling | logstash-9.3 +2 | 9.3.3-r2 | — |
| Wolfi rolling | neo4j-2025.10 +1 | No fix yet | — |
| Wolfi rolling | neo4j-2026.05 | 2026.05.0-r1 | — |
| Wolfi rolling | opensearch-2 | 2.19.4-r14 | — |
| Wolfi rolling | solr-10 | 10.0.0-r1 | — |
| Wolfi rolling | sonarqube | 26.7.0.124771-r0 | — |
| Wolfi rolling | spark-4.0-scala-2.13 | 4.0.2-r11 | — |
| Wolfi rolling | spark-4.1-scala-2.13 | 4.1.1-r15 | — |
| Wolfi rolling | strimzi-kafka-operator-kafka-init +8 | 0.51.0-r22 | — |
| Wolfi rolling | wavefront-proxy | 13.9-r12 | — |
| Wolfi rolling | zipkin | 3.6.1-r4 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| Maven | org.apache.logging.log4j:log4j-core | >= 2.21.0, < 2.25.4 | 2.25.4 | GHSA-445c-vh5m-36rj |
| Maven | org.apache.logging.log4j:log4j-core | >= 3.0.0-beta1, <= 3.0.0-beta3 | — | GHSA-445c-vh5m-36rj |
Advisories 4
- WID-SEC-2026-1067 Apache log4j: Mehrere Schwachstellen ermöglichen Manipulation von Dateien BSI CERT-Bund (WID) · Oct 25, 2026
- WID-SEC-2026-2437 Oracle Communications: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 22, 2026
- WID-SEC-2026-2451 Oracle Siebel CRM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 2, 2026
- WID-SEC-2026-2260 IBM Operational Decision Manager: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 8, 2026
References
- https://github.com/apache/logging-log4j2/pull/4074 patch
- https://logging.apache.org/security.html#CVE-2026-34478 vendor-advisory
- https://logging.apache.org/cyclonedx/vdr.xml vendor-advisory
- https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout related
- https://lists.apache.org/thread/3k1clr2l6vkdnl4cbhjrnt1nyjvb5gwt vendor-advisory