JLine: ReDoS in Built-in Less Viewer Search

Answer in brief

CVE-2026-77423 records a High severity (CVSS 7.5) vulnerability in JLine: ReDoS in Built-in Less Viewer Search. The current sources do not mark it as known exploited. The current feed maps jline/jline3 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 23, 2026Updated Sep 23, 2026Source checked Sep 23, 2026First seen by HOL Sep 23, 2026Material review Sep 23, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps jline/jline3 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
jline/jline3generic	>=3.0.0 <3.30.15 \|\| >=4.0.0 <4.3.1	3.30.15, 4.3.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for jline/jline3.
Review the reported fix. Update jline/jline3 to 3.30.15 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 23, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 23, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.