Linux Kernel BT virtio_bt Header Length Check VULN CVE-2026-46186
CVE-2026-46186 Published on May 28, 2026
Bluetooth: virtio_bt: validate rx pkt_type header length
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: virtio_bt: validate rx pkt_type header length
virtbt_rx_handle() reads the leading pkt_type byte from the RX skb
and forwards the remainder to hci_recv_frame() for every
event/ACL/SCO/ISO type, without checking that the remaining payload
is at least the fixed HCI header for that type.
After the preceding patch bounds the backend-supplied used.len to
[1, VIRTBT_RX_BUF_SIZE], a one-byte completion still reaches
hci_recv_frame() with skb->len already pulled to 0. If the byte
happened to be HCI_ACLDATA_PKT, the ACL-vs-ISO classification
fast-path in hci_dev_classify_pkt_type() dereferences
hci_acl_hdr(skb)->handle whenever the HCI device has an active
CIS_LINK, BIS_LINK, or PA_LINK connection, reading two bytes of
uninitialized RX-buffer data. The same hazard exists for every
packet type the driver accepts because none of the switch cases in
virtbt_rx_handle() check skb->len against the per-type minimum HCI
header size before handing the frame to the core.
After stripping pkt_type, require skb->len to cover the fixed
header size for the selected type (event 2, ACL 4, SCO 3, ISO 4)
before calling hci_recv_frame(); drop ratelimited otherwise.
Unknown pkt_type values still take the original kfree_skb() default
path.
Use bt_dev_err_ratelimited() because both the length and pkt_type
values come from an untrusted backend that can otherwise flood the
kernel log.
Products Associated with CVE-2026-46186
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Affected Versions
Linux:- Version 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be and below 1e1e509b6fd2a42421745bbcd98bd16daad20904 is affected.
- Version 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be and below 2c1143564c71e7497b42d8360a8379ccbb011d3c is affected.
- Version 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be and below 3485c7236c59c8c34a41af1c4b52982437554e79 is affected.
- Version 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be and below f743eab6486965f276c7e3f1700895f014fdc6db is affected.
- Version 160fbcf3bfb93c3c086427f9f4c8bc70f217e9be and below daf23014e5d975e72ea9c02b5160d3fcf070ea47 is affected.
- Version cf2719a21fdb9d4c8e9c834d279163609bef575d is affected.
- Version 9b67438e315b925a699f0178f4a48baf3d2d6ef4 is affected.
- Version 5.15.78 and below 5.16 is affected.
- Version 6.0.8 and below 6.1 is affected.
- Version 6.1 is affected.
- Before 6.1 is unaffected.
- Version 6.6.140, <= 6.6.* is unaffected.
- Version 6.12.88, <= 6.12.* is unaffected.
- Version 6.18.30, <= 6.18.* is unaffected.
- Version 7.0.7, <= 7.0.* is unaffected.
- Version 7.1-rc3, <= * is unaffected.