CVE-1999-1085: SSH Secure Shell

Medium severity, CVSS 5.0. EPSS: 3.5% chance of exploitation in the next 30 days.

SSH 1.2.25, 1.2.23, and other versions, when used in in CBC (Cipher Block Chaining) or CFB (Cipher Feedback 64 bits) modes, allows remote attackers to insert arbitrary data into an existing stream between an SSH client and server by using a known plaintext attack and computing a valid CRC-32 checksum for the packet, aka the "SSH insertion attack."

Affected products

• SSH Secure Shell: version 1.2.23 only; version 1.2.25 only

Published 1998-06-12. Last modified 2026-06-16.