The sysrq_sysctl_handler function in kernel/sysctl.c in the Linux kernel before 2.6.39 does not require the CAP_SYS_ADMIN capability to modify the dmesg_restrict value, which allows local users to bypass intended access restrictions and read the kernel ring buffer by leveraging root privileges, as demonstrated by a root user in a Linux Containers (aka LXC) environment.
CVSS Severity (version 2.0):
Impact Subscore: 6.9
Exploitability Subscore: 1.9
CVSS Version 2 Metrics:
Access Vector: Locally exploitable
Access Complexity: High
Authentication: Not required to exploit
Impact Type: Allows unauthorized disclosure of information
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[oss-security] 20111026 Re: CVE Request -- kernel: sysctl: restrict write access to dmesg_restrict