SB2015081408 - Fedora 21 update for openssh
Published: August 14, 2015 Updated: April 24, 2025
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 3 secuirty vulnerabilities.
1) Permissions, Privileges, and Access Controls (CVE-ID: CVE-2015-5600)
The vulnerability allows a remote non-authenticated attacker to #BASIC_IMPACT#.
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.
2) Input validation error (CVE-ID: CVE-2015-6563)
The vulnerability allows a local user to impersonate other users on the system.
The monitor component in sshd in OpenSSH before 7.0 on non-OpenBSD platforms accepts extraneous username data in MONITOR_REQ_PAM_INIT_CTX requests, which allows local users to conduct impersonation attacks by leveraging any SSH login access in conjunction with control of the sshd uid to send a crafted MONITOR_REQ_PWNAM request, related to monitor.c and monitor_wrap.c.
3) Use-after free (CVE-ID: CVE-2015-6564)
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a use after free error within the mm_answer_pam_free_ctx() function in monitor.c in sshd daemon on non-OpenBSD platforms. A local unprivileged user can send an unexpected early MONITOR_REQ_PAM_FREE_CTX request and gain root privileges on the system.
Remediation
Install update from vendor's website.