Input validation error in konsole - CVE-2025-49091

Vulnerability identifier: #VU110673

CSH Severity: Critical

CVSS v4: 7.5 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2025-49091

CWE-ID: CWE-20

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to compromise the affected system.

The vulnerability exists due to insufficient validation of telnet://URL scheme. A remote attacker can trick the victim into clicking on a specially crafted URL and execute arbitrary console commands on the system with privileges of the current user. 

The vulnerability affects installations without telnet client installed. 

konsole
Arch Linux
Gentoo Linux
Debian Linux
Fedora
Ubuntu
konsole (Red Hat package)
konsole (Ubuntu package)
konsole5
konsole (Debian package)
kde-apps/konsole
konsole

Install updates from vendor's website.

As a temporary solution you can install the telnet client, or delete the file:
/usr/share/applications/ktelnetservice6.desktop

konsole - update to 25.04.2
konsole (Red Hat package) - update to 4.10.5-5.el7_9.1
konsole (Ubuntu package) - addressed in versions 4:15.12.3-0ubuntu1+esm1, 4:17.12.3-1ubuntu1+esm1, 4:19.12.3-0ubuntu1+esm1, 4:21.12.3-0ubuntu1+esm1, 4:23.08.5-0ubuntu4+esm1
konsole5 - addressed in versions 22.04.1-2.el8, 23.08.5-2.el9
konsole (Debian package) - update to 4:22.12.3-1+deb12u1
kde-apps/konsole - update to 24.12.3-r1
konsole - update to 25.04.2-1

• https://kde.org/info/security/advisory-20250609-1.txt

• Remote code execution when handling telnet:// URI in KDE Konsole
• Arch Linux update for konsole
• Fedora EPEL 8 update for konsole5
• Fedora EPEL 9 update for konsole5
• Gentoo update for Konsole
• Debian update for konsole
• Red Hat Enterprise Linux 7 Extended Lifecycle Support update for konsole
• Ubuntu update for konsole