EUVD-2026-45343
GHSA-47qp-hqvx-6r3f
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Pre-auth network-reachable NEW-ENVIRON parsing (AV:N/PR:N/UI:N) with trivially automatable heap flooding (AC:L) yielding a crash only, so C:N/I:N/A:H.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
4Blast Radius
ecosystem impact- 1 maven packages depend on org.jline:jline-remote-telnet (1 direct, 0 indirect)
Ecosystem-wide dependent count for version 4.2.1.
DescriptionCVE.org
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.
AnalysisAI
Unauthenticated remote denial of service in the JLine3 remote-telnet server module (versions before 3.30.14, 4.0.16, and 4.2.1) lets an attacker crash the JVM by flooding the Telnet NEW-ENVIRON negotiation with unbounded unique environment-variable pairs. Because TelnetIO.readNEVariables() stores every pair in an uncapped HashMap on ConnectionData before login, roughly 3-4 MB of traffic can exhaust a 512 MB heap and force an OutOfMemoryError. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires that the target application embeds and exposes the JLine3 remote-telnet server module (org.jline:jline-remote-telnet) with a reachable Telnet listener; the attacker must be able to reach that TCP port and reach the pre-login Telnet option-negotiation phase where the NEW-ENVIRON (RFC 1572) option is handled. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The supplied CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, base 7.5) is internally consistent with the description: fully network-reachable, low complexity, no privileges, no user interaction, availability-only impact. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker locates an exposed JLine3 Telnet service and connects without credentials, since NEW-ENVIRON negotiation happens before login. After completing WILL/DO option negotiation, they send a single NEW-ENVIRON IS subnegotiation packing hundreds of thousands of unique 1-byte variable pairs before the terminating IAC SE, and the accumulating HashMap exhausts the JVM heap and throws OutOfMemoryError, taking the service down; the vendor advisory documents this proof-of-concept methodology, though no packaged exploit tool is identified. |
| Remediation | Upgrade the org.jline:jline-remote-telnet (and JLine3) dependency to a patched release - Vendor-released patch: 3.30.14, 4.0.16, or 4.2.1, choosing the one matching your current branch (3.30.x, 4.0.x, or 4.2.x). … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours: inventory systems running vulnerable JLine3 versions (prior to 3.30.14, 4.0.16, and 4.2.1) and determine whether the remote-telnet module is active in production. …
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External POC / Exploit Code
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