Inadequate encryption strength in OpenSSH - CVE-2023-48795
Published: December 19, 2023 / Updated: January 31, 2025
Vulnerability identifier: #VU84537
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear
CVE-ID: CVE-2023-48795
CWE-ID: CWE-326
Exploitation vector: Remote access
Exploit availability:
Public exploit is available
Vendor: OpenSSH
Affected software:
OpenSSH
OpenSSH
Detailed vulnerability description
The vulnerability allows a remote attacker to perform MitM attack.
The vulnerability exists due to incorrect implementation of the SSH Binary Packet Protocol (BPP), which mishandles the handshake phase and the use of sequence numbers. A remote attacker can perform MitM attack and delete the SSH2_MSG_EXT_INFO message sent before authentication starts, allowing the attacker to disable a subset of the keystroke timing obfuscation features introduced in OpenSSH 9.5.
The vulnerability was dubbed "Terrapin attack" and it affects both client and server implementations.
How to mitigate CVE-2023-48795
Install updates from vendor's website.