What’s Vulnerable › Vulnerabilities

CVE-2026-77423: JLine: ReDoS in Built-in Less Viewer Search

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-23 · updated 2026-09-30
• Weakness: CWE-1333

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.

Affected products

• jline3: from 3.0.0, < 3.30.15; from 4.0.0, < 4.3.1

References

• https://github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541
• https://github.com/jline/jline3/commit/341ee69ccc57b7733c1b40d6993219b64b3206ae
• https://github.com/jline/jline3/pull/2012
• https://github.com/jline/jline3/pull/2018
• https://github.com/jline/jline3/releases/tag/4.3.1
• https://github.com/jline/jline3/releases/tag/jline-3.30.15
• https://github.com/jline/jline3/security/advisories/GHSA-2v9w-34q6-wpqx
• https://github.com/jline/jline3/security/advisories/GHSA-2v9w-34q6-wpqx

Get alerted when CVE-2026-77423 or the next vulnerability affects your stack