CVE-2026-93206 PCI/proc: Use file_ns_capable() when checking config space read access
An unprivileged process can read full PCI config space via procfs if a privileged process opens the file and passes the descriptor, bypassing access controls.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93206?
CVE-2026-93206 is a vulnerability in Linux, published on 24 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-93206?
How do I fix CVE-2026-93206?
Apply the vendor's patch.
Is CVE-2026-93206 being exploited?
There is no known exploitation of CVE-2026-93206 in the wild and no public exploit code.
Sources
Also known as AZL-103940, BELL-CVE-2026-93206, DEBIAN-CVE-2026-93206, GHSA-fjc2-7frc-hj2c, UBUNTU-CVE-2026-93206.