CVE-2026-56740: CWE-400: Uncontrolled Resource Consumption in jline jline3
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.
AI Analysis
Technical Summary
The JLine3 Java library's Telnet server remote-telnet module does not limit the number of environment variables a client can inject via the Telnet NEW-ENVIRON option. The method TelnetIO.readNEVariables() stores each variable pair in a HashMap within ConnectionData without restriction. An unauthenticated attacker can exploit this by flooding the server with unique variable pairs before the terminating IAC SE byte, leading to JVM heap exhaustion and an OutOfMemoryError. Versions 3.30.14, 4.0.16, and 4.2.1 include fixes that address this vulnerability.
Potential Impact
Exploitation allows an unauthenticated remote attacker to cause a denial of service by exhausting the JVM heap memory of the affected application, resulting in an OutOfMemoryError and potential service disruption. There is no impact on confidentiality or integrity reported.
Mitigation Recommendations
Fixed versions 3.30.14, 4.0.16, and 4.2.1 of JLine3 address this vulnerability. Users should upgrade to one of these versions or later to remediate the issue. Patch status is confirmed by the vendor advisory indicating these versions contain the fix.
CVE-2026-56740: CWE-400: Uncontrolled Resource Consumption in jline jline3
Description
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.
CVSS v3.1
Score 7.5high
Affected software
pkg:maven/org.jline/jline3Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The JLine3 Java library's Telnet server remote-telnet module does not limit the number of environment variables a client can inject via the Telnet NEW-ENVIRON option. The method TelnetIO.readNEVariables() stores each variable pair in a HashMap within ConnectionData without restriction. An unauthenticated attacker can exploit this by flooding the server with unique variable pairs before the terminating IAC SE byte, leading to JVM heap exhaustion and an OutOfMemoryError. Versions 3.30.14, 4.0.16, and 4.2.1 include fixes that address this vulnerability.
Potential Impact
Exploitation allows an unauthenticated remote attacker to cause a denial of service by exhausting the JVM heap memory of the affected application, resulting in an OutOfMemoryError and potential service disruption. There is no impact on confidentiality or integrity reported.
Mitigation Recommendations
Fixed versions 3.30.14, 4.0.16, and 4.2.1 of JLine3 address this vulnerability. Users should upgrade to one of these versions or later to remediate the issue. Patch status is confirmed by the vendor advisory indicating these versions contain the fix.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-22T19:17:28.959Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a5b401834329bf928c7134a
Added to database: 07/18/2026, 08:58:00 UTC
Last enriched: 07/18/2026, 08:59:36 UTC
Last updated: 07/18/2026, 11:08:17 UTC
Views: 4
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