CVE-2026-90257 Bluetooth: virtio_bt: avoid OOB read of build info string
A local attacker with Bluetooth access can trigger an out-of-bounds read in the Linux kernel, leaking adjacent memory contents to logs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-90257?
CVE-2026-90257 is a vulnerability in Linux, published on 17 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:
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.
Which versions are affected by CVE-2026-90257?
How do I fix CVE-2026-90257?
Apply the vendor's patch.
Is CVE-2026-90257 being exploited?
There is no known exploitation of CVE-2026-90257 in the wild and no public exploit code.
Sources
Also known as AZL-102251, BELL-CVE-2026-90257, DEBIAN-CVE-2026-90257, GHSA-jc9v-mfxc-m9mm, UBUNTU-CVE-2026-90257.