---
cve: "CVE-2026-56741"
severity: "HIGH"
cvss: 7.5
epss: "53%"
vendor: "jline"
kev: false
exploited: false
published: "2026-07-17 22:17:57"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-11T11:27:31+02:00"
---

# CVE-2026-56741

> 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 apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. 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-2r2c-cx56-8933>
- <https://github.com/jline/jline3/pull/2000>
- <https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708>
- <https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e>
- <https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3>
- <https://github.com/jline/jline3/releases/tag/4.0.16>
- <https://github.com/jline/jline3/releases/tag/4.2.1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-56741) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_