CVE-2026-74508
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk17th percentile - higher than 17% of all known CVEs
Summary
In the Linux kernel, in the Bluetooth HIDP subsystem, a vulnerability was found where data is read before checking if the frame contains a transaction header. The functions hidp_recv_ctrl_frame() and hidp_recv_intr_frame() read skb->data[0] before checking that the L2CAP SDU contains a transaction header. A connected HIDP peer can send an empty basic-mode SDU, leading to use of an uninitialized byte. The fix pulls the transaction header with skb_pull_data() and discards frames that do not contain it.
Risk Assessment
The vulnerability may lead to disclosure of uninitialized memory or manipulation of HIDP session behavior, which could be exploited for DoS or privilege escalation.
Recommendation
Apply a Linux kernel update containing the fix for CVE-2026-74508. Restrict Bluetooth access for untrusted devices.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: HIDP: reject frames without a transaction header hidp_recv_ctrl_frame() and hidp_recv_intr_frame() read skb->data[0] before checking that the L2CAP SDU contains a transaction header. A connected HIDP peer can send an empty basic-mode SDU and make both paths use an uninitialized byte from skb tailroom. KMSAN reports the use in hidp_session_run(), with the uninitialized value originating in __alloc_skb() through vhci_write(). The control path produces two reports and the interrupt path produces one. The byte can also be controlled by a malformed lower-layer packet. If an HCI ACL packet contains an L2CAP PDU with a declared zero-length payload followed by an extra 0x15 byte, l2cap_recv_acldata() reduces skb->len to the declared PDU length before dispatch. The current HIDP path nevertheless consumes the extra byte as HIDP_TRANS_HID_CONTROL | HIDP_CTRL_VIRTUAL_CABLE_UNPLUG and terminates the HIDP session. With this change, the same packet is discarded and a subsequent feature report request succeeds. Pull the transaction header with skb_pull_data() and discard frames that do not contain it.