CVE-2026-93206

Status: UPDATED  |  Advisory ID: CVE-2026-93206

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

PCI/proc: Use file_ns_capable() when checking config space read access

proc_bus_pci_read() decides how much of the config space is readable based

on capable(CAP_SYS_ADMIN), which checks the credentials of the task calling

read(), not the credentials of the process that opened the file.

The sysfs equivalent, pci_read_config(), has checked the credentials of the

opening process since commit de139a339395 ("pci: check caps from sysfs file

open to read device dependent config space"), so a privileged process can

open the config space file and pass the file descriptor to an unprivileged

process (for example, a process running a KVM guest with an assigned

device), which can then read the entire config space. The check was

subsequently routed through the LSM framework in commit 47970b1b2aa6 ("pci:

use security_capable() when checking capablities during config space read")

and converted to the dedicated helper in commit ab0fa82b2df9 ("pci-sysfs:

use proper file capability helper function").

Thus, the two interfaces check the same capability against different

credentials. Checking the credentials of the task calling read() makes the

outcome depend on who reads rather than who opened, so the restriction is

bypassed whenever a more privileged process reads through the descriptor.

Checking the credentials recorded in file->f_cred settles the decision at

open() time and ties it to the file, where it cannot change with the

caller.

Use file_ns_capable() to check CAP_SYS_ADMIN against the credentials in

effect when the file was opened, bringing the procfs interface in line with

the sysfs behaviour.

As a result, a file descriptor opened by a privileged process and passed to

an unprivileged one now allows the entire config space to be read through

procfs, matching sysfs. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References