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TI-2026-26737 Aliases CVE-2026-34479GHSA-h383-gmxw-35v2

Apache Log4j 1 to Log4j 2 bridge: Silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters

Priority LOW 37CWE-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: 1 fixed, 10 without a fix

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

Summary

The Log4j1XmlLayout from the Apache Log4j 1-to-Log4j 2 bridge fails to escape characters forbidden by the XML 1.0 standard, producing malformed XML output. Conforming XML parsers are required to reject documents containing such characters with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records. Two groups of users are affected: * Those using Log4j1XmlLayout directly in a Log4j Core 2 configuration file. * Those using the Log4j 1 configuration compatibility layer with org.apache.log4j.xml.XMLLayout specified as the layout class. Users are advised to upgrade to Apache Log4j 1-to-Log4j 2 bridge version 2.25.4, which corrects this issue. Note: The Apache Log4j 1-to-Log4j 2 bridge is deprecated and will not be present in Log4j 3. Users are encouraged to consult the Log4j 1 to Log4j 2 migration guide https://logging.apache.org/log4j/2.x/migrate-from-log4j1.html , and specifically the section on eliminating reliance on the bridge.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00544 45th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial Apache Log4j 1 to Log4j 2 bridge (Apache Software Foundation): 2.25.4org.apache.logging.log4j:log4j-core (Maven): 2.25.4Red Hat: 1 advisoryRed Hat: 1 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 1 to Log4j 2 bridge2.7 to before 2.25.4; 3.0.0-alpha1 – 3.0.0-beta22.25.4Patch availableCNA
—org.apache.logging.log4j:log4j-core (Maven)2.7 to before 2.25.42.25.4Patch availableGHSA-h383-gmxw-35v2
—org.apache.logging.log4j:log4j-core (Maven)3.0.0-beta1 – 3.0.0-beta2—No fix listedGHSA-h383-gmxw-35v2
  • Apache Log4j 1 to Log4j 2 bridge VendorApache Affected 2.7 to before 2.25.4; 3.0.0-alpha1 – 3.0.0-beta2 Fixed in 2.25.4 Patch available CNA
  • org.apache.logging.log4j:log4j-core (Maven) Vendor— Affected 2.7 to before 2.25.4 Fixed in 2.25.4 Patch available GHSA-h383-gmxw-35v2
  • org.apache.logging.log4j:log4j-core (Maven) Vendor— Affected 3.0.0-beta1 – 3.0.0-beta2 Fixed in — No fix listed GHSA-h383-gmxw-35v2

CPE configurations NVD · 6

CPEVersionsRoleVendor
cpe:2.3:a:apache:log4j:*:*:*:*:*:*:*:*2.7 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:*:*:*:*:*:*:*:* Versions 2.7 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

Remediation

  • Fix · CNA Apache Log4j 1 to Log4j 2 bridge (Apache Software Foundation) Fixed in 2.25.4
  • Fix · GHSA-h383-gmxw-35v2 org.apache.logging.log4j:log4j-core (Maven) Fixed in 2.25.4 Advisory →

Red Hat 1 advisory

  • 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

Vendor assessments

Red Hat

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

ProductStatusPlan or fix
Red Hat Data Grid 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix planned: Out of support scope
Red Hat Fuse 7AffectedNo fix yet: Fix deferred
Red Hat JBoss Enterprise Application Platform 7AffectedNo fix yet: Fix deferred
Red Hat JBoss Enterprise Application Platform 8AffectedNo fix yet: Fix deferred
Red Hat JBoss Enterprise Application Platform Expansion PackAffectedNo fix yet: Fix deferred
Red Hat Offline Knowledge PortalAffectedNo fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)AffectedNo fix yet: Fix deferred
streams for Apache Kafka 3AffectedNo fix yet: Fix deferred
Red Hat Offline Knowledge Portal 1.2.13Fixed RHSA-2026:21773

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34479
  2. 2026-10-03 Alias added: GHSA-h383-gmxw-35v2
  3. 2026-10-25 EPSS moved to the below the 50th percentile

References

Exploit 1

Advisory 4

Other 3

  • 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