CVE-2016-0739 Weak cryptography in n/a

Medium 5.9 Published 13 Apr 2016 Updated 5 Aug 2024

Man-in-the-middle attackers can decrypt or intercept SSH sessions due to improper truncation of ephemeral secrets in libssh key exchange methods.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2016-0739?

CVE-2016-0739 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 13 Apr 2016. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

libssh before 0.7.3 improperly truncates ephemeral secrets generated for the (1) diffie-hellman-group1 and (2) diffie-hellman-group14 key exchange methods to 128 bits, which makes it easier for man-in-the-middle attackers to decrypt or intercept SSH sessions via unspecified vectors, aka a "bits/bytes confusion bug."

Weakness: CWE-200

Which versions are affected by CVE-2016-0739?

It affects 5 products.

Linux distribution packages (11)

`libssh` Red Hat:rhel_extras_other:7	All versions	`0:0.7.1-2.el7`
`libssh-debuginfo` Red Hat:rhel_extras_other:7	All versions	`0:0.7.1-2.el7`
`libssh-devel` Red Hat:rhel_extras_other:7	All versions	`0:0.7.1-2.el7`
`libssh` SUSE:Linux Enterprise Desktop 11 SP4	All versions	`0.2-5.22.1`
`libssh` SUSE:Linux Enterprise Desktop 12	All versions	`0.6.3-11.1`
`libssh` SUSE:Linux Enterprise Desktop 12 SP1	All versions	`0.6.3-11.1`
`libssh` SUSE:Linux Enterprise Software Development Kit 11 SP4	All versions	`0.2-5.22.1`
`libssh` SUSE:Linux Enterprise Software Development Kit 12	All versions	`0.6.3-11.1`
`libssh` SUSE:Linux Enterprise Software Development Kit 12 SP1	All versions	`0.6.3-11.1`
`libssh` SUSE:Linux Enterprise Workstation Extension 12	All versions	`0.6.3-11.1`
`libssh` SUSE:Linux Enterprise Workstation Extension 12 SP1	All versions	`0.6.3-11.1`

Products include Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Libssh Libssh, Redhat Enterprise Linux.

How do I fix CVE-2016-0739?

Upgrade to a fixed version.

Is CVE-2016-0739 being exploited?

There is no known exploitation of CVE-2016-0739 in the wild and no public exploit code.

All Canonical Ubuntu Linux vulnerabilities

Sources

Also known as DEBIAN-CVE-2016-0739, DLA-425-1, DSA-3488-1, GHSA-v7q8-7g48-2272, MGASA-2016-0082, RHSA-2016:0566 and 3 more.