CVE-2026-31497: Bluetooth: btusb: clamp SCO altsetting table indices

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-22 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btusb: clamp SCO altsetting table indices btusb_work() maps the number of active SCO links to USB alternate settings through a three-entry lookup table when CVSD traffic uses transparent voice settings. The lookup currently indexes alts[] with data->sco_num - 1 without first constraining sco_num to the number of available table entries. While the table only defines alternate settings for up to three SCO links, data->sco_num comes from hci_conn_num() and is used directly. Cap the lookup to the last table entry before indexing it so the driver keeps selecting the highest supported alternate setting without reading past alts[].

Affected products

Linux kernel: from 5.8.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.131; from 6.7 before 6.12.80; from 6.13 before 6.18.21 — fixed in 5.10.253, 5.15.203, 6.1.168, 6.12.80, 6.18.21, 6.19.11

How to fix

Upgrade to a fixed version: Linux kernel 5.10.253, 5.15.203, 6.1.168, 6.12.80. Check the vendor advisory for mitigations.

References

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