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[ CVE-2026-77420 · Published 23 Sep 2026 ]

JLine: ReDoS via `HISTORY_IGNORE` Configuration Variable

CVSS 5.5 EPSS <1%Fix available

[ Why it matters ]Priority signals

  • Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, DefaultHistory.matchPatterns(String patterns, String line) in reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java converts the HISTORY_IGNORE configuration value into a Java regular expression while escaping only part of its syntax, allowing other regex metacharacters to reach the backtracking engine. An attacker who can control application or user configuration can supply a nested-quantifier expression that is reevaluated whenever a command is added to history, consuming excessive CPU and indefinitely blocking the reader thread. This issue is fixed in versions 3.30.15 and 4.3.1.

[ Fixes ]Fixes and patches

  • org.jline:jline-reader 4.3.1Fixed version · GitHub Advisories · maven package org.jline:jline-reader: upgrade to 4.3.1 or later (affected >= 4.0.0, < 4.3.1)
  • org.jline:jline-reader 3.30.15Fixed version · GitHub Advisories · maven package org.jline:jline-reader: upgrade to 3.30.15 or later (affected >= 3.0.0, < 3.30.15)

[ Packages ]Affected open-source packages

  • org.jline:jline-reader mavenAffected >= 4.0.0, < 4.3.1 · fixed in 4.3.1 · GHSA-5q95-hrpc-m3w3
  • org.jline:jline-reader mavenAffected >= 3.0.0, < 3.30.15 · fixed in 3.30.15 · GHSA-5q95-hrpc-m3w3

[ References ]References