CVE-2026-56740
Published:July 17, 2026
Updated:August 04, 2026
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 limit the number of environment variables a client may inject via the Telnet NEW-ENVIRON option, and TelnetIO.readNEVariables() in TelnetIO.java:1127-1180 stores each variable pair in a HashMap held by ConnectionData, allowing an unauthenticated attacker to flood unique variable pairs before the terminating IAC SE byte and exhaust JVM heap memory with an OutOfMemoryError. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1.
Affected Packages
https://github.com/jline/jline3.git (GITHUB):
Affected version(s) >=jline-3.27.0 <jline-3.30.14Fix Suggestion:
Update to version jline-3.30.14https://github.com/jline/jline3.git (GITHUB):
Affected version(s) >=4.0.0 <4.2.1Fix Suggestion:
Update to version 4.2.1org.jline:jline-remote-telnet (JAVA):
Affected version(s) >=3.2.0 <4.2.1Fix Suggestion:
Update to version 4.2.1org.jline:jline-remote-telnet (JAVA):
Affected version(s) >=4.0.0 <4.2.1Fix Suggestion:
Update to version 4.2.1org.jline:jline-remote-telnet (JAVA):
Affected version(s) >=3.2.0 <3.30.14Fix Suggestion:
Update to version 3.30.14Related Resources (12)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Uncontrolled Resource Consumption
EPSS
Base Score:
0.50