Vulnerability · Published Sep 23, 2026 · Assigned by GitHub_M
CVE-2026-77423JLine: ReDoS in Built-in Less Viewer Search
High 7.5
In plain English
A high-severity regular-expression denial of service in jline3 from jline. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities).
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | jline3 | no fix listed | DEBIAN-CVE-2026-77423 |
| Debian:13 | jline3 | no fix listed | DEBIAN-CVE-2026-77423 |
| Debian:14 | jline3 | no fix listed | DEBIAN-CVE-2026-77423 |
| Ubuntu:22.04:LTS | jline | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:24.04:LTS | jline | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:26.04:LTS | jline | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:26.10 | jline | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:22.04:LTS | jline2 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:24.04:LTS | jline2 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:26.04:LTS | jline2 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:26.10 | jline2 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:22.04:LTS | jline3 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:24.04:LTS | jline3 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:26.04:LTS | jline3 | no fix listed | UBUNTU-CVE-2026-77423 |
| Ubuntu:26.10 | jline3 | no fix listed | UBUNTU-CVE-2026-77423 |
Affected products (as reported)
Weakness: CWE-1333 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/jline/jline3/security/advisories/GHSA-2v9w-34q6-wpqx x_refsource_CONFIRM
- https://github.com/jline/jline3/pull/2012 x_refsource_MISC
- https://github.com/jline/jline3/pull/2018 x_refsource_MISC
- https://github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541 x_refsource_MISC
- https://github.com/jline/jline3/commit/341ee69ccc57b7733c1b40d6993219b64b3206ae x_refsource_MISC
- https://github.com/jline/jline3/releases/tag/4.3.1 x_refsource_MISC
- https://github.com/jline/jline3/releases/tag/jline-3.30.15 x_refsource_MISC