---
id: CVE-2026-77423
title: JLine is a Java library for handling console input
summary: >-
  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/ma…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-1333
vendor: jline
product: jline3
affected:
  - 'jline3 >= 3.0.0, < 3.30.15'
  - 'jline3 >= 4.0.0, < 4.3.1'
published: '2026-09-23'
updated: '2026-09-24'
sourceUpdated: '2026-09-24T14:18:17.137'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77423'
references:
  - url: >-
      https://github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541
    label: security-advisories@github.com
  - url: >-
      https://github.com/jline/jline3/commit/341ee69ccc57b7733c1b40d6993219b64b3206ae
    label: security-advisories@github.com
  - url: 'https://github.com/jline/jline3/pull/2012'
    label: security-advisories@github.com
  - url: 'https://github.com/jline/jline3/pull/2018'
    label: security-advisories@github.com
  - url: 'https://github.com/jline/jline3/releases/tag/4.3.1'
    label: security-advisories@github.com
  - url: 'https://github.com/jline/jline3/releases/tag/jline-3.30.15'
    label: security-advisories@github.com
  - url: 'https://github.com/jline/jline3/security/advisories/GHSA-2v9w-34q6-wpqx'
    label: security-advisories@github.com
  - url: 'https://github.com/jline/jline3/security/advisories/GHSA-2v9w-34q6-wpqx'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-77423.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-77423'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2539649'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-77423'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-77423'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-24T14:10:41.490849Z'
ingestedAt: '2026-09-23T19:31:04.467Z'
epss: 0.00385
epssPercentile: 0.29786
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Important · affected: Red Hat Fuse 7, Red Hat OpenShift AI (RHOAI), Red Hat OpenStack Platform 13 (Queens) · no fix planned: Red Hat Fuse 7, Red Hat OpenStack Platform 13 (Queens), Red Hat OpenShift AI (RHOAI) · updated 2026-09-24 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-77423.json)