CVE-2026-56740
JLine: Unauthenticated Remote Memory Exhaustion via Unbounded Telnet NEW-ENVIRON Variables
Using jline3 by jline?
Get instant alerts when new vulnerabilities affect jline3 - before attackers find them.
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.
Affected
Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.
Remediation
No guide yetNo remediation guidance has been written for this CVE yet. What the record does show:
Patch and advisory references
- https://github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3f
- https://github.com/jline/jline3/commit/0389f0ee6d0375901b602671ad5dafd4d1d4ee09
- https://github.com/jline/jline3/commit/4ee3a73849ffb9a85ec748e4e8cd8f6d81f84f40
- https://github.com/jline/jline3/commit/934f09e6128cee33c2b13d42b6e859c1ee2d194b
References (9)
SSVC — Action Prioritization
SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.
CVSS
- Attack Vector
- NETWORK
- Complexity
- LOW
- Privileges
- NONE
- User Interaction
- NONE
- Scope
- UNCHANGED
- Confidentiality
- NONE
- Integrity
- NONE
- Availability
- HIGH
Quick Info
Get alerted
Stop reading CVE feeds looking for your own stack
Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.