Public Date:
680841: CVE-2011-1021 kernel: /sys/kernel/debug/acpi/custom_method can bypass module restrictions

The MITRE CVE dictionary describes this issue as:

drivers/acpi/debugfs.c in the Linux kernel before 3.0 allows local users to modify arbitrary kernel memory locations by leveraging root privileges to write to the /sys/kernel/debug/acpi/custom_method file. NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-4347.

Find out more about CVE-2011-1021 from the MITRE CVE dictionary dictionary and NIST NVD.


The version of Linux kernel as shipped with Red Hat Enterprise Linux 4, 5, and 6 as they did not include upstream commit a1a541d8 and a25ee920 that introduced the problem. This has been addressed in Red Hat Enterprise MRG via


This requires debugfs to be mounted on a local system in order to have access
to the custom_method file. Debugfs is not mounted by default. You need to run
"mount -t debugfs nodev /sys/kernel/debug" as root first.

CVSS v2 metrics

Base Score 6
Base Metrics AV:L/AC:H/Au:S/C:C/I:C/A:C
Access Vector Local
Access Complexity High
Authentication Single
Confidentiality Impact Complete
Integrity Impact Complete
Availability Impact Complete

Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).

Red Hat Security Errata

Platform Errata Release Date
Red Hat MRG Grid for RHEL 6 Server v.2 (kernel-rt) RHSA-2011:1253 2011-09-12
Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.
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