What’s Vulnerable › Vulnerabilities

CVE-2026-77420: JLine: ReDoS via `HISTORY_IGNORE` Configuration Variable

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% 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, DefaultHistory.matchPatterns(String patterns, String line) in reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java converts the HISTORY_IGNORE configuration value into a Java regular expression while escaping only part of its syntax, allowing other regex metacharacters to reach the backtracking engine. An attacker who can control application or user configuration can supply a nested-quantifier expression that is reevaluated whenever a command is added to history, consuming excessive CPU and indefinitely blocking the reader thread. 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-5q95-hrpc-m3w3
• https://github.com/jline/jline3/security/advisories/GHSA-5q95-hrpc-m3w3

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