CVE-2026-56740
Last modified
CVE-2026-56740 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.50% chance of exploitation in the next 30 days.
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.
Metrics
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Jline | Jline | < 3.30.14 |
| Jline | Jline | >= 4.0.0, < 4.0.16 |
| Jline | Jline | >= 4.1.0, < 4.2.1 |
References
- https://github.com/jline/jline3/pull/2000Issue Tracking
- https://github.com/jline/jline3/pull/2001Issue 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-47qp-hqvx-6r3fExploit, Vendor Advisory
- https://github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3fExploit, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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How Strix Helps
- 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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