Vulnerability in Jline Jline3
CVE-2026-77423
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.
Vulnerability class: ReDoS (Regular Expression Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.005 (40.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 40th percentile — 40.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001
Affected products
- Jline Jline3 — versions >= 3.0.0, < 3.30.15, >= 4.0.0, < 4.3.1
Weakness classification (CWE)
References
- github.com/jline/jline3/security/advisories/GHSA-2v9w-34q6-wpqx
- github.com/jline/jline3/pull/2012
- github.com/jline/jline3/pull/2018
- github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541
- github.com/jline/jline3/commit/341ee69ccc57b7733c1b40d6993219b64b3206ae
- github.com/jline/jline3/releases/tag/4.3.1
- github.com/jline/jline3/releases/tag/jline-3.30.15
Frequently asked questions
- What is CVE-2026-77423?
- CVE-2026-77423 is a high-severity vulnerability in Jline Jline3, classified under Inefficient Regular Expression Complexity. CVSS score: 7.5/10. Published 2026-09-23.
- How severe is CVE-2026-77423?
- High severity. CVSS v3 base score is 7.5 out of 10.