CVE-2026-90257: Bluetooth: virtio_bt: avoid OOB read of build info string

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-17 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: virtio_bt: avoid OOB read of build info string The virtbt_setup_zephyr() sends the Zephyr vendor command 0xfc08 (Read Build Information) and hands the response to bt_dev_info() and hci_set_fw_info() as a "%s" string starting at skb->data + 1, without checking the length. A backend that answers with status only leaves that pointer past the end of the received data, so the walk reads adjacent slab memory until it meets a NUL. Those bytes reach the kernel log and the firmware-info debugfs file. To fix this, print the string with a bounded "%.*s" limited to skb->len - 1. A short or unterminated response then prints as much as arrived instead of failing setup. This mirrors commit dd068ef04412 ("Bluetooth: bpa10x: avoid OOB read of revision string in bpa10x_setup()"), which fixed the identical pattern.

Affected products

Linux kernel: 5.13 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux kernel 7.3. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-90257 or the next vulnerability affects your stack