Description
Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets producing invalid XML output whenever a log message or MDC value contains such characters.
The impact depends on the StAX implementation in use:
* JRE built-in StAX: Forbidden characters are silently written to the output, producing malformed XML. Conforming parsers must reject such documents with a fatal error, which may cause downstream log-processing systems to drop the affected records.
* Alternative StAX implementations (e.g., Woodstox https://github.com/FasterXML/woodstox , a transitive dependency of the Jackson XML Dataformat module): An exception is thrown during the logging call, and the log event is never delivered to its intended appender, only to Log4j's internal status logger.
Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue by sanitizing forbidden characters before XML output.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Apache Software Foundation | Apache Log4j Core | 2.0-alpha1 – < 2.25.4, 3.0.0-alpha1 – ≤ 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.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | apache-log4j2 +1 | No fix yet | — |
| Debian 13 | apache-log4j2 +1 | No fix yet | — |
| Debian 12 | apache-log4j2 +1 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 26.04 LTS | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 25.10 | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 24.04 LTS | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 22.04 LTS | apache-log4j2 +1 | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | apache-log4j2 +1 | No fix yet | — |
| Ubuntu 18.04 LTS | apache-log4j2 +1 | 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 | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | log4j | 2.20.0-2.1 | openSUSE-SU-2026:10544-1 |
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 | apache-tika-3.1 | 3.1.0-r30 | — |
| Wolfi rolling | apache-tika-3.2 | 3.2.3-r9 | — |
| Wolfi rolling | apache-tika-3.2-compat | 3.2.3-r18 | — |
| Wolfi rolling | celeborn-0.6 | 0.6.2-r13 | — |
| Wolfi rolling | druid | 36.0.0-r13 | — |
| Wolfi rolling | flink-2.1 | 2.1.1-r3 | — |
| Wolfi rolling | flink-2.2 | 2.2.0-r5 | — |
| Wolfi rolling | infinispan-16.1 | 16.1.3-r1 | — |
| 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 | opensearch-3 | 3.5.0-r3 | — |
| 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 | >= 2.0-alpha1, < 2.25.4 | 2.25.4 | GHSA-3pxv-7cmr-fjr4 |
| Maven | org.apache.logging.log4j:log4j-core | >= 3.0.0-alpha1, <= 3.0.0-beta3 | — | GHSA-3pxv-7cmr-fjr4 |
Advisories 9
- 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-2026-4084 Oracle Siebel CRM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 20, 2026
- WID-SEC-2026-2444 Oracle Fusion Middleware: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 7, 2026
- NCSC-2026-0378 Kwetsbaarheden verholpen in Oracle Financial Services NCSC-NL (Netherlands) · Sep 16, 2026
- WID-SEC-2026-3398 Oracle Financial Services Applications: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 15, 2026
- NCSC-2026-0259 Kwetsbaarheden verholpen in Oracle Analytics NCSC-NL (Netherlands) · Jul 22, 2026
- WID-SEC-2026-2260 IBM Operational Decision Manager: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jul 8, 2026
- openSUSE-SU-2026:10544-1 log4j-2.20.0-2.1 on GA media SUSE / openSUSE Security Updates · Apr 15, 2026
References
- https://github.com/apache/logging-log4j2/pull/4077 patch
- https://logging.apache.org/security.html#CVE-2026-34480 vendor-advisory
- https://logging.apache.org/cyclonedx/vdr.xml vendor-advisory
- https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout related
- https://lists.apache.org/thread/5x0hcnng0chhghp6jgjdp3qmbbhfjzhb vendor-advisory