---
cve: "CVE-2026-56740"
severity: "HIGH"
cvss: 7.5
epss: "52%"
vendor: "jline"
kev: false
exploited: false
published: "2026-07-17 22:17:57"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-11T12:09:01+02:00"
---

# CVE-2026-56740

> 7.5 HIGH · 🧪 PoC

## Beschreibung

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-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- c02dd469e463c83a1eed433a6565de12cc7234b0 (Commit)
- 86b7ba7801988aadb1a67555629522a71d603bd3 (Commit)

## Referenzen

- <https://github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3f>
- <https://github.com/jline/jline3/pull/2000>
- <https://github.com/jline/jline3/pull/2001>
- <https://github.com/jline/jline3/commit/0389f0ee6d0375901b602671ad5dafd4d1d4ee09>
- <https://github.com/jline/jline3/commit/4ee3a73849ffb9a85ec748e4e8cd8f6d81f84f40>
- <https://github.com/jline/jline3/commit/934f09e6128cee33c2b13d42b6e859c1ee2d194b>
- <https://github.com/jline/jline3/releases/tag/4.0.16>
- <https://github.com/jline/jline3/releases/tag/4.2.1>
- <https://github.com/jline/jline3/releases/tag/jline-3.30.14>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-56740) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_