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.
https://www.openssh.com/txt/release-7.3
http://seclists.org/fulldisclosure/2016/Jul/51
http://www.securityfocus.com/bid/91812
https://security.gentoo.org/glsa/201612-18
http://www.securitytracker.com/id/1036319
https://www.exploit-db.com/exploits/40136/
https://www.exploit-db.com/exploits/40113/
http://www.debian.org/security/2016/dsa-3626
https://access.redhat.com/errata/RHSA-2017:2563
https://access.redhat.com/errata/RHSA-2017:2029
https://security.netapp.com/advisory/ntap-20190206-0001/
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
Source: MITRE
Published: 2017-02-13
Updated: 2022-12-13
Type: CWE-200
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.9
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Impact Score: 3.6
Exploitability Score: 2.2
Severity: MEDIUM