CVE-2026-77423: Jline JLINE3

High severity, CVSS 7.5. EPSS: 0.4% chance of exploitation in the next 30 days.

JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, the JLine built-in less viewer passes user-controlled search and display-filter patterns from getPattern(boolean doDisplayPattern) in builtins/src/main/java/org/jline/builtins/Less.java directly to Java's backtracking regular expression engine and repeatedly applies them to file content. A nested-quantifier expression evaluated against non-matching lines can consume excessive CPU and indefinitely block the session thread, and repeated sessions in Telnet or SSH deployments can exhaust a bounded worker pool. This issue is fixed in versions 3.30.15 and 4.3.1.

Affected products

• Jline JLINE3: from 3.0.0, before 3.30.15 (fixed in 3.30.15); from 4.0.0, before 4.3.1 (fixed in 4.3.1)

Published 2026-09-23. Last modified 2026-09-30.