CVE-2026-56741

JLine is a Java library for handling console input. Prior to 3.30.14, 4.0.16, and 4.2.1, the JLine3 Telnet server remote-telnet module does not apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1.

• CWE-400

• https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708Patch
• https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393ePatch
• https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3Patch
• https://github.com/jline/jline3/pull/2000Issue Tracking
• https://github.com/jline/jline3/releases/tag/4.0.16Release Notes
• https://github.com/jline/jline3/releases/tag/4.2.1Release Notes
• https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933Vendor Advisory, Exploit
• https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933Vendor Advisory, Exploit

Published

Jul 17, 2026

Last Modified

Aug 18, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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