Logback 1.6.3

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.