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.
History

Fri, 25 Sep 2026 05:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Thu, 24 Sep 2026 09:45:00 +0000

Type Values Removed Values Added
First Time appeared Jline
Jline jline
Vendors & Products Jline
Jline jline

Thu, 24 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Important


Wed, 23 Sep 2026 18:45:00 +0000

Type Values Removed Values Added
Description 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.
Title JLine: ReDoS in Built-in Less Viewer Search
Weaknesses CWE-1333
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published: 2026-09-23T18:17:49.635Z

Updated: 2026-09-24T14:10:52.736Z

Reserved: 2026-08-20T19:59:59.603Z

Link: CVE-2026-77423

cve-icon Vulnrichment

Updated: 2026-09-24T14:10:25.326Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-23T19:19:16.017

Modified: 2026-09-30T16:44:39.840

Link: CVE-2026-77423

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-23T18:17:49Z

Links: CVE-2026-77423 - Bugzilla