It was discovered that the OpenSSH sshd daemon did not check the list of keyboard-interactive authentication methods for duplicates. A remote attacker could use this flaw to bypass the MaxAuthTries limit, making it easier to perform password guessing attacks.
Find out more about CVE-2015-5600 from the MITRE CVE dictionary dictionary and NIST NVD.
This issue does not affect the default OpenSSH sshd configuration in Red Hat Enterprise Linux 4, 5, 6 and 7.
| Base Score | 4.3 |
|---|---|
| Base Metrics | AV:N/AC:M/Au:N/C:N/I:P/A:N |
| Access Vector | Network |
| Access Complexity | Medium |
| Authentication | None |
| Confidentiality Impact | None |
| Integrity Impact | Partial |
| Availability Impact | None |
Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).
| Platform | Errata | Release Date |
|---|---|---|
| Red Hat Enterprise Linux 7 (openssh) | RHSA-2015:2088 | 2015-11-19 |
| Red Hat Enterprise Linux 6 (openssh) | RHSA-2016:0466 | 2016-03-21 |
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 5 | openssh | Will not fix |
| Red Hat Enterprise Linux 4 | openssh | Will not fix |
This issue can be mitigated by disabling keyboard-interactive authentication method. That can be achieved by setting "ChallengeResponseAuthentication no" in the /etc/ssh/sshd_config configuration file and restarting the sshd service.
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