Bluetooth: MGMT: reject HCI_CMD_SYNC params_len above 255

Summary

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: MGMT: reject HCI_CMD_SYNC params_len above 255 mgmt_hci_cmd_sync() checks that the message length agrees with params_len but puts no upper bound on it. params_len is __le16 while the parameter length in the HCI command header is a u8: struct hci_command_hdr { __le16 opcode; __u8 plen; } __packed; hci_cmd_sync_alloc() assigns one to the other: hdr->plen = plen; if (plen) skb_put_data(skb, param, plen); so a params_len of 256 leaves plen at 0 while all 256 bytes are still appended. The frame handed to the driver then declares no parameters and carries 256 of them. On a length framed transport such as H:4 the controller takes the trailing bytes as the start of the next packet. The mgmt socket MTU is HCI_MAX_FRAME_SIZE, so params_len can reach about 1KB this way. Commit 03f1700b9b4d ("Bluetooth: MGMT: reject malformed HCI_CMD_SYNC commands") only made params_len agree with the message length, a value that fits the message but not the header field is still accepted. Reject params_len that does not fit the header field.

Timeline

1. Sep 4, 2026, 3:12 PM UTCCVE published
2. Oct 19, 2026, 8:43 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 827af4787e74e8df9e8e0677a69fbb15e0856d2f · fixed in b7d9edcf9fe6e9ec3a2e80ef9e8d44ef9b4f2894; From 827af4787e74e8df9e8e0677a69fbb15e0856d2f · fixed in 0bd0195ce25737cbdd0eabc54319ee0ddf3a0ad2; From 827af4787e74e8df9e8e0677a69fbb15e0856d2f · fixed in 6e1c44878aa3ee7336efeaf01414b030b0a5c273; From 827af4787e74e8df9e8e0677a69fbb15e0856d2f · fixed in 5d95286b6d6e8f1d304da7522bfa6860fc017e48

• Linux Linux

  6.13

• KernelLinux

  From 6.13.0 · fixed in 6.18.47; From 6.19.0 · fixed in 7.1.11; From 7.2.0 · fixed in 7.2.1

References 4