Bug 2539649 (CVE-2026-77423)

Summary:	CVE-2026-77423 org.jline/jline: JLine: Denial of Service via user-controlled regular expressions
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	asyoung, eglynn, gmalinko, janstey, jhollowa, jjoyce, jpretori, jschluet, kaycoth, lhh, mburns, mgarciac, pdelbell, prichard, rstepani, sthirugn
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
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Doc Text:	A flaw was found in JLine. The built-in less viewer processes user-controlled search and display-filter patterns using Java's backtracking regular expression engine. A remote attacker could provide a specially crafted regular expression, leading to excessive CPU consumption and indefinitely blocking the session thread. This can result in a Denial of Service (DoS) for affected systems, especially in Telnet or SSH deployments where repeated sessions could exhaust worker pools.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	2539773
Bug Blocks:

Description OSIDB Bzimport 2026-09-23 18:43:28 UTC

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.