CVE-2026-46123
Description
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: virtio_bt: clamp rx length before skb_put virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one(). Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device. The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory. Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle(). Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log. Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
Mitigation details
CVE-2026-46123 NameCVE-2026-46123 DescriptionIn the Linux kernel, the following vulnerability has been resolved: Bluetooth: virtio_bt: clamp rx length before skb_put virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly…
CVE-2026-46123
| Name | CVE-2026-46123 |
| Description | In the Linux kernel, the following vulnerability has been resolved: Bluetooth: virtio_bt: clamp rx length before skb_put virtbt_rx_work() calls skb_put(skb, len) where len comes directly from virtqueue_get_buf() with no validation against the buffer we posted to the device. The RX skb is allocated in virtbt_add_inbuf() and exposed to virtio as exactly 1000 bytes via sg_init_one(). Checking len against skb_tailroom(skb) is not sufficient because alloc_skb() can leave more tailroom than the 1000 bytes actually handed to the device. A malicious or buggy backend can therefore report used.len between 1001 and skb_tailroom(skb), causing skb_put() to include uninitialized kernel heap bytes that were never written by the device. The same path also accepts len == 0, in which case skb_put(skb, 0) leaves the skb empty but virtbt_rx_handle() still reads the pkt_type byte from skb->data, consuming uninitialized memory. Define VIRTBT_RX_BUF_SIZE once and reuse it in alloc_skb() and sg_init_one(), and gate virtbt_rx_work() on that same constant so the bound checked matches the buffer actually exposed to the device. Reject used.len == 0 in the same gate so an empty completion can no longer reach virtbt_rx_handle(). Use bt_dev_err_ratelimited() because the length value comes from an untrusted backend that can otherwise flood the kernel log. Same class of bug as commit c04db81cd028 ("net/9p: Fix buffer overflow in USB transport layer"), which hardened the USB 9p transport against unchecked device-reported length. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
Vulnerable and fixed packages
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| linux (PTS) | bullseye | 5.10.223-1 | fixed |
| bullseye (security) | 5.10.257-1 | fixed | |
| bookworm | 6.1.170-3 | vulnerable | |
| bookworm (security) | 6.1.174-1 | vulnerable | |
| trixie | 6.12.86-1 | vulnerable | |
| trixie (security) | 6.12.90-2 | fixed | |
| forky | 7.0.9-1 | fixed | |
| sid | 7.0.10-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| linux | source | bullseye | (not affected) | |||
| linux | source | trixie | 6.12.88-1 | |||
| linux | source | (unstable) | 7.0.7-1 |
Notes
[bullseye] - linux <not-affected> (Vulnerable code not present)
https://git.kernel.org/linus/21bd244b6de5d2fe1063c23acc93fbdd2b20d112 (7.1-rc3)
Apply commands
[bullseye] - linux <not-affected> (Vulnerable code not present)https://git.kernel.org/linus/21bd244b6de5d2fe1063c23acc93fbdd2b20d112 (7.1-rc3)OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | affected | |
| debian | bullseye | fixed | 0 |
| debian | forky | fixed | 7.0.7-1 |
| debian | sid | fixed | 7.0.7-1 |
| debian | trixie | fixed | 6.12.88-1 |
References
- https://git.kernel.org/stable/c/21bd244b6de5d2fe1063c23acc93fbdd2b20d112
- https://git.kernel.org/stable/c/6c1730099a6fc18b183bd6c1adad3b54adcaeda9
- https://git.kernel.org/stable/c/b40cdd1b1370d76e9e760af4490cb4a351cceead
- https://git.kernel.org/stable/c/e6b4296f170d949ebba937cf6a3f247ec9550d2c
- https://git.kernel.org/stable/c/ed41c81d30b211a671667259c3b5feeba0e062d5
- https://security-tracker.debian.org/tracker/CVE-2026-46123
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.