SSH Communications Security Information for VU#888801

SSL/TLS implementations disclose side channel information via PKCS #1 v1.5 version number extension



Vendor Statement

SSH Communications Security Vendor statement for VU#888801

Not vulnerable products:

SSH Secure Shell for Servers (all versions)
SSH Secure Shell for Windows Servers (all versions)
SSH Secure Shell for Workstations (all versions)

The ssh1, ssh2 and ssh-agent protocols and applications are not vulnerable to the Klima-Pokorny-Rosa (KPR) attack because no error messages are reported from PKCS1 v1.5 decryption other than invalid PKCS1 padding. This implies there are no effective extensions to the Bleichenbacher attack such as the KPR attack against Secure Shell. The ssh1 and ssh-agent protocols have countermeasures against the Bleichenbacher attack and it is not applicable against ssh2.

Vulnerable products:

SSH Certificate/TLS Toolkit up to and including version 5.1.1
SSH IPSEC Express Toolkit up to and including version 5.1.1

A fix is available and has been delivered to SSH customers.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Vendor References



The CERT/CC has no additional comments at this time.

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