Inefficient regular expression complexity in jline3 - CVE-2026-77421
Published: September 9, 2026
Vulnerability identifier: #VU148440
CSH Severity: Low
CVSS v4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-77421
CWE-ID: CWE-1333
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote user to cause a denial of service.
The vulnerability exists due to inefficient regular expression complexity in the nano editor\'s doSearch(String text) function when processing a user-supplied regular expression in regex search mode. A remote user can enter a crafted nested-quantifier regular expression to cause a denial of service.
Regex search mode must be enabled, and non-matching buffer content can trigger catastrophic backtracking.
Affected software
jline3
How to mitigate CVE-2026-77421
Install security update from vendor's website.
jline3 - addressed in versions 3.30.15, 4.3.1