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2 vulnerabilities found for Apache Log4j 1 to Log4j 2 bridge by Apache Software Foundation
CVE-2026-34479 (GCVE-0-2026-34479)
Vulnerability from nvd – Published: 2026-04-10 15:41 – Updated: 2026-04-10 17:47
VLAI
Title
Apache Log4j 1 to Log4j 2 bridge: Silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters
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.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-116 - Improper Encoding or Escaping of Output
Assigner
References
6 references
| URL | Tags |
|---|---|
| https://github.com/apache/logging-log4j2/pull/4078 | patch |
| https://logging.apache.org/security.html#CVE-2026-34479 | vendor-advisory |
| https://logging.apache.org/cyclonedx/vdr.xml | vendor-advisory |
| https://logging.apache.org/log4j/2.x/migrate-from… | related |
| https://lists.apache.org/thread/gd0hp6mj17rn3kj27… | vendor-advisory |
| http://www.openwall.com/lists/oss-security/2026/04/10/8 |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Apache Software Foundation | Apache Log4j 1 to Log4j 2 bridge |
Affected:
2.7 , < 2.25.4
(maven)
Affected: 3.0.0-alpha1 , ≤ 3.0.0-beta2 (maven) cpe:2.3:a:apache:log4j_1_2_api:*:*:*:*:*:*:*:* |
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CVE-2026-34479 (GCVE-0-2026-34479)
Vulnerability from cvelistv5 – Published: 2026-04-10 15:41 – Updated: 2026-04-10 17:47
VLAI
Title
Apache Log4j 1 to Log4j 2 bridge: Silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters
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.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-116 - Improper Encoding or Escaping of Output
Assigner
References
6 references
| URL | Tags |
|---|---|
| https://github.com/apache/logging-log4j2/pull/4078 | patch |
| https://logging.apache.org/security.html#CVE-2026-34479 | vendor-advisory |
| https://logging.apache.org/cyclonedx/vdr.xml | vendor-advisory |
| https://logging.apache.org/log4j/2.x/migrate-from… | related |
| https://lists.apache.org/thread/gd0hp6mj17rn3kj27… | vendor-advisory |
| http://www.openwall.com/lists/oss-security/2026/04/10/8 |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Apache Software Foundation | Apache Log4j 1 to Log4j 2 bridge |
Affected:
2.7 , < 2.25.4
(maven)
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