#VU15379 Authentication bypass in libssh - CVE-2018-10933
Published: October 17, 2018 / Updated: June 9, 2022
Vulnerability identifier: #VU15379
Vulnerability risk: Low
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Clear
CVE-ID: CVE-2018-10933
CWE-ID: CWE-592
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vulnerable software:
libssh
libssh
Software vendor:
libssh
libssh
Description
The vulnerability allows a remote attacker to bypass authentication on the target system.
The weakness exists due to coding error, when libssh receives the "SSH2_MSG_USERAUTH_SUCCESS" message. A remote attacker can send the SSH server "SSH2_MSG_USERAUTH_SUCCESS" message instead of the "SSH2_MSG_USERAUTH_REQUEST" message that a server usually expects and which libssh uses as a sign that an authentication procedure needs to initiate, bypass authentication procedures and gain access to a server with an SSH connection enabled without having to enter the password.
The weakness exists due to coding error, when libssh receives the "SSH2_MSG_USERAUTH_SUCCESS" message. A remote attacker can send the SSH server "SSH2_MSG_USERAUTH_SUCCESS" message instead of the "SSH2_MSG_USERAUTH_REQUEST" message that a server usually expects and which libssh uses as a sign that an authentication procedure needs to initiate, bypass authentication procedures and gain access to a server with an SSH connection enabled without having to enter the password.
Remediation
The vulnerability has been addressed in the version 0.7.4, 0.8.6.