Improper Certificate Validation

Apache Log4j Core is vulnerable to Improper Certificate Validation. The vulnerability is due to ignored hostname verification settings in TLS configuration, which allows an attacker to perform a man-in-the-middle attack by presenting a trusted certificate and intercepting secure communications...

OPENSUSE-SU-2026:10544-1 log4j-2.20.0-2.1 on GA media

These are all security issues fixed in the log4j-2.20.0-2.1 package on the GA media of openSUSE Tumbleweed...

CVE-2026-34481

A flaw was found in Apache Log4j's JsonTemplateLayout. This vulnerability allows a remote attacker to disrupt log processing systems. By sending log events that include specific non-numeric floating-point values, the attacker can cause the JsonTemplateLayout to generate invalid JSON output. This...

CVE-2026-34479

A flaw was found in the Apache Log4j 1-to-Log4j 2 bridge. The Log4j1XmlLayout component fails to properly escape characters forbidden by the XML 1.0 standard. This improper handling of characters results in malformed XML output, which can cause downstream log processing systems to drop or fail to...

CVE-2026-34477

A flaw was found in Apache Log4j Core. A network-based attacker can perform a man-in-the-middle MITM attack, allowing them to intercept encrypted communications. This occurs when an SMTP, Socket, or Syslog appender uses Transport Layer Security TLS with a nested element, and the attacker has a...

CVE-2026-34480

A flaw was found in Apache Log4j Core. The XmlLayout component, responsible for formatting log messages into XML, does not properly remove or replace characters that are not allowed in XML 1.0. When log messages or diagnostic information contain these forbidden characters, the resulting XML outpu...

Linux Distros Unpatched Vulnerability : CVE-2026-34477

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - The fix for CVE-2025-68161 https://logging.apache.org/security.htmlCVE-2025-68161 was incomplete: it addressed hostname verification only when enabled via the...

Linux Distros Unpatched Vulnerability : CVE-2026-34478

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Apache Log4j Core's Rfc5424Layout https://logging.apache.org/log4j/2.x/manual/layouts.htmlRFC5424Layout , in versions 2.21.0 through 2.25.3, is vulnerable to lo...

Linux Distros Unpatched Vulnerability : CVE-2026-34481

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces inval...

Linux Distros Unpatched Vulnerability : CVE-2026-34480

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available. - Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.htmlXmlLayout , in versions up to and including 2.25.3, fails to sanitize...

Improper Output Handling

Apache Log4j is vulnerable to Improper Output Handling. The vulnerability is due to JsonTemplateLayout generating invalid JSON when processing non-finite floating-point values e.g., NaN, Infinity, which are not compliant with RFC 8259, allowing attacker-controlled data in log events to produce...

GHSA-W35J-PV5H-Q9Q9 Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout

Apache Log4j's JsonTemplateLayout, in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values NaN, Infinity, or -Infinity, which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to ind...

GHSA-H383-GMXW-35V2 Apache Log4j 1 to Log4j 2 bridge: silent log event loss in Log4j1XmlLayout due to unescaped XML 1.0 forbidden characters

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...

Apache Log4j JSON Template Layout: Improper serialization of non-finite floating-point values in JsonTemplateLayout

Apache Log4j's JsonTemplateLayout, in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values NaN, Infinity, or -Infinity, which are prohibited by RFC 8259. This may cause downstream log processing systems to reject or fail to ind...

EUVD-2026-21409

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...

EUVD-2026-21412

Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain non-finite floating-point values NaN, Infinity, or -Infinity, which are prohibited by RFC 8259. Th...

EUVD-2026-21408

Apache Log4j Core's Rfc5424Layout https://logging.apache.org/log4j/2.x/manual/layouts.htmlRFC5424Layout , 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 user...

GHSA-445C-VH5M-36RJ Apache Log4j Core: log injection in `Rfc5424Layout` due to silent configuration incompatibility

Apache Log4j Core's 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:...

GHSA-3PXV-7CMR-FJR4 Apache Log4j Core: Silent log event loss in XmlLayout due to unescaped XML 1.0 forbidden characters

Apache Log4j Core's XmlLayout, in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification, 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...

GHSA-6HG6-V5C8-FPHQ Apache Log4j Core: `verifyHostName` attribute silently ignored in TLS configuration

The fix for CVE-2025-68161 was incomplete: it addressed hostname verification only when enabled via the log4j2.sslVerifyHostName system property, but not when configured through the verifyHostName attribute of the element. Although the verifyHostName configuration attribute was introduced in Log4...