CVE-2026-9828

Deserialization of untrusted data vulnerability in QOS.CH Sarl logback logback-core (HardenedObjectInputStream (logback-core) modules) allows Object Injection albeit heavily restricted.

More precisely, an attacker able to influence serialized data sent to SimpleSocketServer or SimpleSSLSocketServer can instantiate objects from classes in the java.lang and java.util packages that are not explicitly blocked.

Although deserialization is heavily restricted by HardenedObjectInputStream and no practical way to achieve remote code execution or significant privilege escalation has been identified, this issue constitutes a bypass of the intended security restrictions.

This issue affects logback: through 1.5.32 inclusive.

Red Hat Lightwell has released ch.qos.logback:logback-core 1.2.11.rhlw-00001 with backported fixes for CVE-2023-6378, CVE-2024-12798, CVE-2024-12801, CVE-2025-11226, CVE-2026-10532, CVE-2026-1225, and CVE-2026-9828.

CVE-2023-6378: Logback "receiver" DOS vulnerability

CVE-2024-12798: ACE vulnerability in JaninoEventEvaluator by QOS.CH logback-core upto including version 0.1 to 1.3.14 and 1.4.0 to 1.5.12 in Java applications allows attacker to execute arbitrary code by compromising an existing logback configuration file or by injecting an environment variable before program execution.

Malicious logback configuration files can allow the attacker to execute arbitrary code using the JaninoEventEvaluator extension.

A successful attack requires the user to have write access to a configuration file. Alternatively, the attacker could inject a malicious environment variable pointing to a malicious configuration file. In both cases, the attack requires existing privilege.

CVE-2024-12801: Server-Side Request Forgery (SSRF) in SaxEventRecorder by QOS.CH logback version 0.1 to 1.3.14 and 1.4.0 to 1.5.12  on the Java platform, allows an attacker to forge requests by compromising logback configuration files in XML.

The attacks involves the modification of DOCTYPE declaration in  XML configuration files.

CVE-2025-11226: ACE vulnerability in conditional configuration file processing by QOS.CH logback-core up to and including version 1.5.18 in Java applications, allows an attacker to execute arbitrary code by compromising an existing logback configuration file or by injecting an environment variable before program execution.

A successful attack requires the presence of Janino library and Spring Framework to be present on the user's class path. In addition, the attacker must  have write access to a configuration file. Alternatively, the attacker could inject a malicious environment variable pointing to a malicious configuration file. In both cases, the attack requires existing privilege.

CVE-2026-10532: Logback deserialization whitelist bypass for Proxy objects

CVE-2026-1225: ACE vulnerability in configuration file processing by QOS.CH logback-core up to and including version 1.5.24 in Java applications, allows an attacker to instantiate classes already present on the class path by compromising an existing logback configuration file.

The instantiation of a potentially malicious Java class requires that said class is present on the user's class-path. In addition, the attacker must have write access to a configuration file. However, after successful instantiation, the instance is very likely to be discarded with no further ado.

CVE-2026-9828: Logback deserialization whitelist bypass for java.lang and java.util

This patched artifact is a drop-in replacement for ch.qos.logback:logback-core 1.2.11 from Maven Central.

Deserialization of untrusted data vulnerability in QOS.CH Sarl logback logback-core (HardenedObjectInputStream (logback-core) modules) allows Object Injection albeit heavily restricted. More precisely, an attacker able to influence serialized data sent to SimpleSocketServer or SimpleSSLSocketServer can instantiate objects from classes in the java.lang and java.util packages that are not explicitly blocked. Although deserialization is heavily restricted by HardenedObjectInputStream and no practical way to achieve remote code execution or significant privilege escalation has been identified, this issue constitutes a bypass of the intended security restrictions. This issue affects logback: through 1.5.32 inclusive.

These are all security issues fixed in the logback-1.5.34-2.1 package on the GA media of openSUSE Tumbleweed.