2026-08-14 Release of logback version 1.6.3

• In response CVE-2026-19880, MDCBasedDiscriminator (used by SiftingAppender) now strips forward and backward slashes (/, \) from MDC values before they are used as discriminating keys. This prevents path segments from escaping into destinations controlled by an attacker. When sanitisation actually changes a value, a warning is emitted; the warning is rate-limited (a small batch, then a lull of about ten minutes).

• Colour console support is split out into a dedicated JansiConsoleAppender. It wraps stdout or stderr with Jansi so ANSI escape sequences (for example coloured patterns) render correctly on terminals that need it, notably Windows. Prefer this class over the older path described next. See the appenders documentation.

• The withJansi property on ConsoleAppender is deprecated. Existing configurations that still set <withJansi>true</withJansi> continue to work for compatibility, but new setups should use JansiConsoleAppender instead.

• ConsoleAppender no longer treats the process console as an exclusive resource: stopping it does not close System.out / System.err. JansiConsoleAppender pairs each AnsiConsole.systemInstall() with systemUninstall() on stop, so repeated start/stop cycles do not leave Jansi installed or tear down streams shared with the rest of the JVM. Related behavior is covered by tests for issues/1063.

• Invocation throttling helpers were reworked: SimpleInvocationGate is renamed FixedIntervalInvocationGate, and BatchedFixedIntervalInvocationGate allows a short burst of invocations before applying a fixed lull. The sanitisation
  warning above uses the batched gate.

• The JPMS module-info for logback-core now exports the ch.qos.logback.core.property package, which had been missing from the module descriptor.

• A bit-wise identical binary of this version can be reproduced by building from source code at commit e8e824dede022a6d7208b36cfa875b0d1b7772f3 associated with the tag v_1.6.3. The release was built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

--
Sponsoring SLF4J/logback/reload4j at https://github.com/sponsors/qos-ch

2026-08-10 Release of logback version 1.6.2

• Configuration analysis now detects contradictory caller-data inclusion instructions. For example, an AsyncAppender, SocketAppender or SMTPAppender with includeCallerData left at the default false is incompatible with a layout or encoder pattern that uses a caller-data converter such as %C, %M, %L, %F, %l or %caller. At runtime those converters would print question marks and still incur extraction cost on a worker thread. Logback now emits a configuration-time warning when such instructions disagree. See codes.html#callerContradiction for details. This issue was reported in issues/1059 by leeychee. The initial analysis was contributed by seonwoo_jung.

• Caller-contradiction analysis can be turned off by setting the logback.skipCallerContradictionAnalysis variable to true, either as a system property (-Dlogback.skipCallerContradictionAnalysis=true) or as a property in the configuration file:

  <property name="logback.skipCallerContradictionAnalysis" value="true"/>

• SimpleSocketServer and SimpleSSLSocketServer now require an explicit client IP whitelist. On the command line, pass one or more allowed addresses (single IPs or CIDR ranges) after the configuration file. An empty whitelist means no clients are accepted. When embedding the server programmatically, register allowed addresses with addAllowedClientAddress(String) or setAllowedClientAddresses(Collection) before clients connect. See the documentation on restricting client access.

• Added ThrowableProxyVOBuilder for assembling a ThrowableProxyVO field by field, with a corresponding ThrowableProxyVO.builder() entry point.

• Dependency analysis handlers now run their postHandle method after child models have been processed, so checks that depend on nested appenders (such as caller-contradiction analysis) see a complete picture.

• Updated several dependencies, including Angus Mail to 2.0.4 and Jetty (test) to 12.1.12.

• A bit-wise identical binary of this version can be reproduced by building from source code at commit e3d7833 associated with the tag v_1.6.2. The release was built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

2026-07-28 Release of logback version 1.6.1

• In TimeBasedRollingPolicy, when the file option is set, the intermediate file renamed before asynchronous compression now receives the target archive name without the compression suffix (e.g. .gz, .zip, .xz). Previously it used a nanotime-based .tmp suffix. This makes the file easier to identify if compression fails during rollover. (See also the following paragraph.)

• On GZ, ZIP, or XZ compression failure, the original (uncompressed) log file is no longer deleted. Compression strategies now delete the source file only after successful compression and emit a warning that the original was left intact.

• ConsoleAppender with now probes JLine's org.jline.jansi.AnsiConsole first and falls back to the legacy FuseSource org.fusesource.jansi.AnsiConsole class. This keeps ANSI coloring working after Jansi moved under the JLine project. The optional org.jline:jansi-core artifact is declared as a dependency alongside the existing FuseSource jansi dependency. A preferredJansiClassName property was added for tests. This issue was reported in issues/1043 by seonwoo_jung who also provided the relevant PR.

• LayoutWrappingEncoder now reports an error at start() when no layout is set and guards encode() against a null layout. Previously, a missing layout (for example after an ignored // branch) allowed the encoder to start and then fail with a NullPointerException on every event, resulting in silent log loss. This issue was reported in issues/1046 by seonwoo_jung who also provided the relevant PR.

• FileCollisionAnalyser now detects file collisions involving nested appenders of SiftingAppender. When the nested file or fileNamePattern does not textually reference the discriminator key (e.g. ${userId}), a warning is issued at configuration time naming the appender, the key, and the shared target. This closes a gap where statically declared file appenders were checked but sifted nested appenders were not. This enhancement was contributed in PR #1041 by seonwoo_jung.

• More defensive handling in SyslogOutputStream and SyslogAppenderBase: the close() method now ensures that resources are closed, writes and flushes check that the underlying resources are in a valid state and fallback to no-op otherwise.

• A bit-wise identical binary of this version can be reproduced by building from source code at commit 57759f4 associated with the tag v_1.6.1. The release was built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

• See https://logback.qos.ch/news.html#1.6.1 for the original text.

2026-07-23 Release of logback version 1.6.0

• Removed certain deprecated variables, methods, and classes. For the list of removed members see release_1.6.0.txt.

• In AsyncAppenderBase, the put(ILoggingEvent) method now has the protected modifier to allow access from derived classes. This change was requested by Thomas Skjølberg in pr#1053.

• Bump SLF4J dependency to version 2.0.18.

• See also the overview of the 1.6.x series.

• A bit-wise identical binary of this version can be reproduced by building from source code at commit b07adf3 associated with the tag v_1.6.0. The release was built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

2026-07-09 Release of logback version 1.5.38

• In HardenedObjectInputStream, fixed a typo preventing Throwable objects from being white-filtered. This issue was reported in PR #1045 by t0rchwo0d.

• A bitwise identical binary of this version can be reproduced by building from source code at commit d04984a associated with the tag v_1.5.38. Release built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

2026-06-26 Release of logback version 1.5.37

1. • Given the numerous vulnerabilities related to conditional configuration processing based on the evaluation of Java expressions using the Janino library, support for such expressions has been removed. Users are offered the an online migration service or the <condition> element introduced in version 1.5.20. See the relevant documentation for more details.

• A bitwise identical binary of this version can be reproduced by building from source code at commit c1df7f5 associated with the tag v_1.5.37. Release built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

2026-06-25 Release of logback version 1.5.36

• The 'condition' attribute in <if> elements now reject certain references that are associated with ACE attacks. This issue was reported by "yulate" ([email protected]) and registered as CVE-2026-13006. Please note that version 1.5.37 provides the full fix to this vulnerability.

• A bitwise identical binary of this version can be reproduced by building from source code at commit 9b94c37 associated with the tag v_1.5.36. Release built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

026-06-23 Release of logback version 1.5.35

• The 'condition' attribute in <if> elements now rejects unicode escape sequences (\u and \U). This closes a bypass of the existing prohibition on the new operator in Janino-evaluated conditions. This issue was reported by IcySun ([email protected]) and registered as CVE-2026-13006. Please note that version 1.5.37 provides the full fix to this vulnerability.

• Added ConfiguratorRank.AUTHENTICATING (rank 100), the highest configurator rank, for certified/authenticating configurators discovered via the ServiceLoader mechanism. ContextInitializer now requires that at most one such configurator exist on the classpath; if more than one is found, initialization aborts with an error.

• ConsoleCharsetPropertyDefiner is no longer shipped. The Java 21 multi-release compilation of logback-core has been disabled, which removes this class from the published artifact. Configurations that referenced ch.qos.logback.core.property.ConsoleCharsetPropertyDefiner will need an alternative approach for console charset detection.

• The logback-examples module is now included in artifacts published to Maven Central.

• JoranConfigurator.makeAnotherInstance() and DefaultJoranConfigurator.performMultiStepConfigurationFileSearch() are now protected, allowing derived configurators to override these methods.

• A bitwise identical binary of this version can be reproduced by building from source code at commit 08bd159 associated with the tag v_1.5.35. Release built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

2026-06-01 Release of logback version 1.5.34

• In case certain StackTraceElement values returned by the Throwable.getStackTrace method are null, StackTraceElementProxy substitutes a dummy instance instead of throwing an IllegalArgumentException. This resolves issues #1040, reported by Naotsugu Kobayashi.

• HardenedObjectInputStream will now throw an InvalidClassException during deserialization attempts of Proxy classes. This change addresses potential deserialization whitelist bypass vulnerability reported by York Shen and registered as CVE-2026-10532.

• A bitwise identical binary of this version can be reproduced by building from source code at commit e62272a associated with the tag v_1.5.34. This release was built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.

2026-05-27 Release of logback version 1.5.33

• PropertiesConfiguratorModelHandler now registers properties file URLs to the ConfigurationWatchList when scan is enabled (via local scan="true" attribute or top-level configuration scan), ensuring changes are detected and reconfiguration occurs. This problem was reported in issues/1034.

• When processing <conversionRule> elements and both class and converterClass attributes are specified, silently use the class attribute without issuing a warning. However, if the attribute values differ, a warning will be issued. This change was requested in issues/1031.

• HardenedModelInputStream will no longer accept to deserialize all classes located under the "java.lang" and "java.util" packages but a limited number of explicitly authorized classes in those packages. This potential deserialization whitelist bypass vulnerability was reported by York Shen and registered as CVE-2026-9828.

• SSL parameters for SSLSocketAppender now enable hostname verification by default. Moreover, the default protocol is now "TLSv1.2". This potential vulnerability was reported by York Shen.

• When printing the status message field, ViewStatusMessagesServletBase now escapes special characters such as "&" as character entities. This potential vulnerability was reported by York Shen.

• A bit-wise identical binary of this version can be reproduced by building from source code at commit 124e8b4 associated with the tag v_1.5.33. Release built using Java "21" 2023-10-17 LTS build 21.0.1.+12-LTS-29 under Linux Debian 11.6.