Vulnerability in Jline Jline3
CVE-2026-77421
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 nano editor's regex search mode passes a user-controlled search term from doSearch(String text) in builtins/src/main/java/org/jline/builtins/Nano.java to Java's backtracking regular expression engine without a timeout or backtracking bound. A nested-quantifier expression evaluated against non-matching buffer content can consume excessive CPU and indefinitely block the editor session thread, and remote multi-user deployments can lose a worker thread for each affected session. 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 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.004 (37.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.7% 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: 0.004 · change: 0.000
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-ph9c-7hw9-vhhw
- 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-2026-77421?
- CVE-2026-77421 is a medium-severity vulnerability in Jline Jline3, classified under Inefficient Regular Expression Complexity. CVSS score: 6.5/10. Published 2026-09-23.
- How severe is CVE-2026-77421?
- Medium severity. CVSS v3 base score is 6.5 out of 10.