CVE-2011-4080

Severity: medium (CVSS 4.0 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2012-05-24 · updated 2026-06-16
Weakness: CWE-264

Description

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.

Affected products

Linux kernel: before 2.6.39 — fixed in 2.6.39

How to fix

Upgrade to a fixed version: Linux kernel 2.6.39. Check the vendor advisory for mitigations.

References

http://ftp.osuosl.org/pub/linux/kernel/v2.6/ChangeLog-2.6.39
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=bfdc0b497faa82a0ba2f9dddcf109231dd519fcc
http://www.openwall.com/lists/oss-security/2011/10/26/10
https://github.com/torvalds/linux/commit/bfdc0b497faa82a0ba2f9dddcf109231dd519fcc
http://ftp.osuosl.org/pub/linux/kernel/v2.6/ChangeLog-2.6.39
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git%3Ba=commit%3Bh=bfdc0b497faa82a0ba2f9dddcf109231dd519fcc
http://www.openwall.com/lists/oss-security/2011/10/26/10
https://github.com/torvalds/linux/commit/bfdc0b497faa82a0ba2f9dddcf109231dd519fcc

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