SB2026033102 - Ubuntu update for openssh
Published: March 31, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 secuirty vulnerabilities.
1) Resource management error (CVE-ID: CVE-2026-3497)
The vulnerability allows a local user to perform a denial of service (DoS) attack.
The vulnerability exists due to incorrect handling of disconnecting clients in OpenSSH GSSAPI Key Exchange when GSSAPIKeyExchange setting is enabled. An authenticated user can crash the OpenSSH server or potentially execute arbitrary code.
2) OS Command Injection (CVE-ID: CVE-2025-61984)
The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.
The vulnerability exists due to improper validation of control characters in usernames obtained from an untrusted source (such as command line and %-sequence expansion of a configuration file). A remote attacker can trick the victim into initiating an ssh connection using a specially crafted configuration file and execute arbitrary shell commands on the system.
This vulnerability affects ssh client command and does not affect the sshd daemon.
3) Improper Neutralization of Null Byte or NUL Character (CVE-ID: CVE-2025-61985)
The vulnerability allows a remote attacker to execute arbitrary OS commands on the system.
The vulnerability exists due to incorrect handling of the nullbyte character in an ssh:// URI if a ProxyCommand that uses the %r expansion was configured. A remote attacker can trick the victim into using a specially crafted ssh command to connect to a remote server and execute arbitrary OS commands on the system.
This vulnerability affects ssh client command and does not affect the sshd daemon.
Remediation
Install update from vendor's website.