CVE-2016-6210 Information disclosure in n/a

Medium 5.9 Published 13 Feb 2017 Updated 29 May 2026

Remote attackers can enumerate valid usernames by exploiting timing differences in password hashing when specific algorithms are used.

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

What is CVE-2016-6210?

CVE-2016-6210 is a medium-severity vulnerability in OpenSSH, published on 13 Feb 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

sshd in OpenSSH before 7.3, when SHA256 or SHA512 are used for user password hashing, uses BLOWFISH hashing on a static password when the username does not exist, which allows remote attackers to enumerate users by leveraging the timing difference between responses when a large password is provided.

Weakness: CWE-200

Which versions are affected by CVE-2016-6210?

It affects 1 product.

Linux distribution packages (28)

`openssh` Red Hat:enterprise_linux:6::client	All versions	`0:5.3p1-123.el6_9`
`openssh-askpass` Red Hat:enterprise_linux:6::client	All versions	`0:5.3p1-123.el6_9`
`openssh-clients` Red Hat:enterprise_linux:6::client	All versions	`0:5.3p1-123.el6_9`
`openssh-debuginfo` Red Hat:enterprise_linux:6::client	All versions	`0:5.3p1-123.el6_9`
`openssh-ldap` Red Hat:enterprise_linux:6::client	All versions	`0:5.3p1-123.el6_9`
`openssh-server` Red Hat:enterprise_linux:6::client	All versions	`0:5.3p1-123.el6_9`
`pam_ssh_agent_auth` Red Hat:enterprise_linux:6::client	All versions	`0:0.9.3-123.el6_9`
`openssh` Red Hat:enterprise_linux:6::computenode	All versions	`0:5.3p1-123.el6_9`
`openssh-askpass` Red Hat:enterprise_linux:6::computenode	All versions	`0:5.3p1-123.el6_9`
`openssh-clients` Red Hat:enterprise_linux:6::computenode	All versions	`0:5.3p1-123.el6_9`
`openssh-debuginfo` Red Hat:enterprise_linux:6::computenode	All versions	`0:5.3p1-123.el6_9`
`openssh-ldap` Red Hat:enterprise_linux:6::computenode	All versions	`0:5.3p1-123.el6_9`
`openssh-server` Red Hat:enterprise_linux:6::computenode	All versions	`0:5.3p1-123.el6_9`
`pam_ssh_agent_auth` Red Hat:enterprise_linux:6::computenode	All versions	`0:0.9.3-123.el6_9`
`openssh` Red Hat:enterprise_linux:6::server	All versions	`0:5.3p1-123.el6_9`
`openssh-askpass` Red Hat:enterprise_linux:6::server	All versions	`0:5.3p1-123.el6_9`
`openssh-clients` Red Hat:enterprise_linux:6::server	All versions	`0:5.3p1-123.el6_9`
`openssh-debuginfo` Red Hat:enterprise_linux:6::server	All versions	`0:5.3p1-123.el6_9`
`openssh-ldap` Red Hat:enterprise_linux:6::server	All versions	`0:5.3p1-123.el6_9`
`openssh-server` Red Hat:enterprise_linux:6::server	All versions	`0:5.3p1-123.el6_9`
`pam_ssh_agent_auth` Red Hat:enterprise_linux:6::server	All versions	`0:0.9.3-123.el6_9`
`openssh` Red Hat:enterprise_linux:6::workstation	All versions	`0:5.3p1-123.el6_9`
`openssh-askpass` Red Hat:enterprise_linux:6::workstation	All versions	`0:5.3p1-123.el6_9`
`openssh-clients` Red Hat:enterprise_linux:6::workstation	All versions	`0:5.3p1-123.el6_9`
`openssh-debuginfo` Red Hat:enterprise_linux:6::workstation	All versions	`0:5.3p1-123.el6_9`
`openssh-ldap` Red Hat:enterprise_linux:6::workstation	All versions	`0:5.3p1-123.el6_9`
`openssh-server` Red Hat:enterprise_linux:6::workstation	All versions	`0:5.3p1-123.el6_9`
`pam_ssh_agent_auth` Red Hat:enterprise_linux:6::workstation	All versions	`0:0.9.3-123.el6_9`

Products include OpenSSH.

How do I fix CVE-2016-6210?

Upgrade to a fixed version.

Is CVE-2016-6210 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2016-6210 exists.

Public exploit code: 1 Metasploit module, 2 Exploit-DB entries and 7 proofs of concept on GitHub.

All OpenSSH vulnerabilities

Sources

Also known as ALPINE-CVE-2016-6210, DEBIAN-CVE-2016-6210, DLA-578-1, DSA-3626-1, GHSA-f525-65h3-3qjh, RHSA-2017:2563 and 1 more.