CVE-2015-5600

CVE-2015-5600 is a high-severity vulnerability in Openbsd Openssh with a CVSS 3.x base score of 8.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-264.

Key facts

Description

The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.

Frequently asked questions

What is CVE-2015-5600?
The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.
How severe is CVE-2015-5600?
CVE-2015-5600 has a CVSS 3.x base score of 8.1, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2015-5600 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 9% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-5600?
CVE-2015-5600 affects Openbsd Openssh. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2015-5600?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2015-5600 published?
CVE-2015-5600 was published on 2015-08-03 and last updated on 2026-06-17.

References

Affected products (1)

More vulnerabilities in Openbsd Openssh

All CVEs affecting Openbsd Openssh →

Other CWE-264 (Permissions, Privileges, and Access Controls) vulnerabilities

Browse all CWE-264 (Permissions, Privileges, and Access Controls) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE: