Linux Picks Up Fix For Latest "Confused Deputy" Weakness Going Back To 2.6.12 Kernel

Written by Michael Larabel in Linux Security on 26 May 2021 at 01:23 PM EDT. 2 Comments
Merged today to Linux 5.13 Git and marked for back-porting to stable series is a new "confused deputy" weakness and affects kernels going back to Linux 2.6.12 from 2005.

Merged today is a proc code change to check writes against the file opener for the /proc/$pid/attr/ area where security attributes are handled for a given process.

As explained by Kees Cook of Google and longtime Linux kernel developer, "Fix another "confused deputy" weakness. Writes to /proc/$pid/attr/ files need to check the opener credentials, since these fds do not transition state across execve(). Without this, it is possible to trick another process (which may have different credentials) to write to its own /proc/$pid/attr/ files, leading to unexpected and possibly exploitable behaviors."

More details on the "confused deputy" weakness privilege escalation attacks via the kernel documentation or for a broader overview of the situation via Wikipedia.
Related News
About The Author
Michael Larabel

Michael Larabel is the principal author of and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and automated benchmarking software. He can be followed via Twitter, LinkedIn, or contacted via

Popular News This Week