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TI-2026-26738 Aliases CVE-2026-34480GHSA-3pxv-7cmr-fjr4

Apache Log4j Core: Silent log event loss in XmlLayout due to unescaped XML 1.0 forbidden characters

Priority LOW 39CWE-116Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · None · None
Fix status
Partial Red Hat: 9 fixed, 10 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01064 64th percentileScored 2026-11-07
Fix Partial Apache Log4j Core (Apache Software Foundation): 2.25.4org.apache.logging.log4j:log4j-core (Maven): 2.25.4Red Hat: 9 advisoriesRed Hat: 9 fixed, 10 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ApacheApache Log4j Core2.0-alpha1 to before 2.25.4; 3.0.0-alpha1 – 3.0.0-beta32.25.4Patch availableCNA
—org.apache.logging.log4j:log4j-core (Maven)2.0-alpha1 to before 2.25.42.25.4Patch availableGHSA-3pxv-7cmr-fjr4
—org.apache.logging.log4j:log4j-core (Maven)3.0.0-alpha1 – 3.0.0-beta3—No fix listedGHSA-3pxv-7cmr-fjr4
  • Apache Log4j Core VendorApache Affected 2.0-alpha1 to before 2.25.4; 3.0.0-alpha1 – 3.0.0-beta3 Fixed in 2.25.4 Patch available CNA
  • org.apache.logging.log4j:log4j-core (Maven) Vendor— Affected 2.0-alpha1 to before 2.25.4 Fixed in 2.25.4 Patch available GHSA-3pxv-7cmr-fjr4
  • org.apache.logging.log4j:log4j-core (Maven) Vendor— Affected 3.0.0-alpha1 – 3.0.0-beta3 Fixed in — No fix listed GHSA-3pxv-7cmr-fjr4

CPE configurations NVD · 7

CPEVersionsRoleVendor
cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*2.0 to before 2.25.4VulnerableApache
cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:*3.0.0 alpha1VulnerableApache
cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:*3.0.0 alpha1_rc1VulnerableApache
cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:*3.0.0 alpha1_rc2VulnerableApache
cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:*3.0.0 beta1VulnerableApache
cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:*3.0.0 beta2VulnerableApache
cpe:2.3:a:apache:log4j:3.0.0:beta3:*:*:*:*:*:*3.0.0 beta3VulnerableApache
  • cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:* Versions 2.0 to before 2.25.4 Vulnerable ·Apache
  • cpe:2.3:a:apache:log4j:3.0.0:alpha1:*:*:*:*:*:* Versions 3.0.0 alpha1 Vulnerable ·Apache
  • cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc1:*:*:*:*:*:* Versions 3.0.0 alpha1_rc1 Vulnerable ·Apache
  • cpe:2.3:a:apache:log4j:3.0.0:alpha1_rc2:*:*:*:*:*:* Versions 3.0.0 alpha1_rc2 Vulnerable ·Apache
  • cpe:2.3:a:apache:log4j:3.0.0:beta1:*:*:*:*:*:* Versions 3.0.0 beta1 Vulnerable ·Apache
  • cpe:2.3:a:apache:log4j:3.0.0:beta2:*:*:*:*:*:* Versions 3.0.0 beta2 Vulnerable ·Apache
  • cpe:2.3:a:apache:log4j:3.0.0:beta3:*:*:*:*:*:* Versions 3.0.0 beta3 Vulnerable ·Apache

Remediation

  • Fix · CNA Apache Log4j Core (Apache Software Foundation) Fixed in 2.25.4
  • Fix · GHSA-3pxv-7cmr-fjr4 org.apache.logging.log4j:log4j-core (Maven) Fixed in 2.25.4 Advisory →

Red Hat 9 advisories

  • RHSA-2026:66545 Released 2026-09-10 · Red Hat rating Important
    Red Hat AMQ Broker 7.13.6 release and security update
    • Red Hat AMQ Broker 7.13.6
  • RHSA-2026:66488 Released 2026-09-10 · Red Hat rating Important
    Red Hat AMQ Broker 7.14.1 release and security update
    • Red Hat AMQ Broker 7.14.1
  • RHSA-2026:54435 Released 2026-08-12 · Red Hat rating Important
    Streams for Apache Kafka 3.2.1 release and security update
    • Streams for Apache Kafka 3.2.1
Show 6 more Red Hat advisories
  • RHSA-2026:42644 Released 2026-07-21 · Red Hat rating Important
    RHOAI 2.25.9 - Red Hat OpenShift AI
    • Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-caikit-tgis-serving-rhel9, registry.redhat.io/rhoai/odh-feature-server-rhel9, registry.redhat.io/rhoai/odh-kserve-storage-initializer-rhel9 +36
  • RHSA-2026:37390 Released 2026-07-09 · Red Hat rating Important
    Red Hat Build of Apache Camel 4.18.1.P1 for Spring Boot release.
    • Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16
  • RHSA-2026:34608 Released 2026-07-02 · Red Hat rating Important
    Streams for Apache Kafka 2.9.4 release and security update
    • Streams for Apache Kafka 2.9.4
  • RHSA-2026:25089 Released 2026-06-10 · Red Hat rating Important
    HawtIO 4.4.0 for Red Hat build of Apache Camel 4 Release and security update.
    • HawtIO HawtIO 4.4.0
  • RHSA-2026:22619 Released 2026-06-02 · Red Hat rating Important
    Red Hat Data Grid 8.6.1 security update
    • Red Hat Data Grid 8.6.1
  • RHSA-2026:21773 Released 2026-05-28 · Red Hat rating Important
    Red Hat Offline Knowledge Portal security and content update
    • Red Hat Offline Knowledge Portal 1.2.13 registry.redhat.io/offline-knowledge-portal/rhokp-rhel9

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Apache Log4j Core 2.25.4

    3 records Highest priority Priority LOW 3 LOW

    Other records, highest priority first

    • TI-2026-26736 Apache Log4j Core: Log injection in Rfc5424Layout due to silent configuration incompatibilityPriority LOW 38
    • TI-2026-26735 Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypassPriority LOW 29
    Show all 3 records →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat AI Inference ServerAffectedNo fix planned: Will not fix
Red Hat Enterprise Linux 9AffectedNo fix planned: Will not fix
Red Hat Enterprise Linux AI (RHEL AI) 3AffectedNo fix yet
Red Hat Fuse 7AffectedNo fix planned: Will not fix
Red Hat JBoss Enterprise Application Platform 7AffectedNo fix planned: Will not fix
Red Hat Offline Knowledge PortalAffectedNo fix yet
Red Hat OpenShift AI (RHOAI)AffectedNo fix planned: Will not fix
Red Hat build of Apicurio Registry 2AffectedNo fix planned: Will not fix
Red Hat build of Apicurio Registry 3AffectedNo fix planned: Will not fix
Red Hat build of OptaPlanner 8AffectedNo fix yet
HawtIO HawtIO 4.4.0Fixed RHSA-2026:25089
Red Hat AMQ Broker 7.13.6Fixed RHSA-2026:66545
Red Hat AMQ Broker 7.14.1Fixed RHSA-2026:66488
Red Hat Data Grid 8.6.1Fixed RHSA-2026:22619
Red Hat Offline Knowledge Portal 1.2.13Fixed RHSA-2026:21773
Red Hat OpenShift AI 2.25Fixed RHSA-2026:42644
Red Hat build of Apache Camel 4.18.1.P1 for Spring Boot 3.5.16Fixed RHSA-2026:37390
Streams for Apache Kafka 2.9.4Fixed RHSA-2026:34608
Streams for Apache Kafka 3.2.1Fixed RHSA-2026:54435
Not affected: 8 products
  • Red Hat AI Inference Server
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat JBoss Enterprise Application Platform 8
  • Red Hat JBoss Enterprise Application Platform Expansion Pack
  • Red Hat JBoss Web Server 6
  • Red Hat OpenShift AI (RHOAI)
  • Red Hat OpenShift AI 2.25

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34480
  2. 2026-10-03 Alias added: GHSA-3pxv-7cmr-fjr4
  3. 2026-10-10 Affected versions changed · Red Hat
  4. 2026-10-13 Fix available: HawtIO HawtIO 4.4.0 · Red Hat
  5. 2026-10-14 Fix available: RHSA-2026:25089 · Red Hat
  6. 2026-10-16 Affected versions changed · Red Hat
  7. 2026-10-30 Affected versions changed · Red Hat
  8. 2026-11-06 Fix available: RHSA-2026:42644 · Red Hat

References

Patch 1

Advisory 5

Other 2

  • TI-2021-19919 Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints KEVCVSS 3.1CRITICAL 10.0
  • TI-2021-20393 Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack KEVCVSS 3.1CRITICAL 9.0
  • TI-2017-03645 Deserialization of untrusted data in Apache Log4j CVSS 3.1CRITICAL 9.8
  • TI-2019-13113 Deserialization of untrusted data in Apache Log4j CVSS 3.1CRITICAL 9.8
  • TI-2022-07428 SQL injection in JDBC Appender in Apache Log4j V1 CVSS 3.1CRITICAL 9.8
  • TI-2022-07425 Deserialization of untrusted data in JMSSink in Apache Log4j 1.x CVSS 3.1HIGH 8.8
See all 19 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences