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 products
jline: jline
References10
- github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3f ExploitVendor Advisory
- github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3f ExploitVendor Advisory
- github.com/jline/jline3/commit/0389f0ee6d0375901b602671ad5dafd4… Patch
- github.com/jline/jline3/commit/4ee3a73849ffb9a85ec748e4e8cd8f6d… Patch
- github.com/jline/jline3/commit/934f09e6128cee33c2b13d42b6e859c1… Patch
- github.com/jline/jline3/pull/2000 Issue Tracking
- github.com/jline/jline3/pull/2001 Issue Tracking
- github.com/jline/jline3/releases/tag/4.0.16 Release Notes
- github.com/jline/jline3/releases/tag/4.2.1 Release Notes
- github.com/jline/jline3/releases/tag/jline-3.30.14 Release Notes
Metrics
- CVSS 3.1
-
7.5
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - EPSS — exploit probability
- 1% percentile: 49 · as of 14 November 2026
- CWE
- CWE-400
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.