Microsoft security update for CVE-2026-46186 — azl3 kernel 6.6.139.1-1 on Azure Linux 3.0
🔗 CVE IDs covered (1)
📋 Microsoft's advisory
EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-46186. This page also shows what EchelonGraph holds for CVE-2026-46186, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.
🎯 Affected products1
- azl3 kernel 6.6.139.1-1 on Azure Linux 3.0
✅ Updates Microsoft lists: 1 update
1 row: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.
| KB article | Update | Fixed build |
|---|---|---|
| — | Security Update | 6.6.141.1-1 |
🧭 EchelonGraph on CVE-2026-46186
- EchelonGraph score
- 5.5 MEDIUM
- CISA KEV
- Not listed
- Fix status
- A fix is available — apply it.
Description from the CVE record (CVE.org), as published by its numbering authority
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.
Published by kernel.org, the CVE Numbering Authority that assigned CVE-2026-46186, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).