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Fencer Intel
high 7.7

CVE-2026-46123 json

Bluetooth: virtio_bt: clamp rx length before skb_put

published 5mo ago modified 3mo ago also EUVD-2026-32882

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

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.

Patch / fix

  • Linux Linux 5.15.209, 6.1, 6.1.175, 6.6.140, 6.12.88, 6.18.30, 7.0.7, 7.1
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.88-1
  • linux Debian 14 7.0.7-1

debian advisories DEBIAN-CVE-2026-46123

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux Ubuntu 26.04 LTS 7.0.0-28.28
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1009.9
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72

ubuntu advisories UBUNTU-CVE-2026-46123

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 10.2 6.12.0-211.53.1.el10_2
  • rv RHEL 10.2 6.12.0-211.53.1.el10_2
  • perf RHEL 10.2 6.12.0-211.53.1.el10_2
  • rtla RHEL 10.2 6.12.0-211.53.1.el10_2
  • libperf RHEL 10.2 6.12.0-211.53.1.el10_2
  • kernel-rt RHEL 10.2 6.12.0-211.53.1.el10_2
  • kernel-64k RHEL 10.2 6.12.0-211.53.1.el10_2
  • kernel-core RHEL 10.2 6.12.0-211.53.1.el10_2

red hat advisories RHSA-2026:65334

  • kernel-default SLES 16.0, SLE High Availability Extension 16.0, Linux Micro 6.2 +1 more 6.12.0-160000.37.1
  • kernel-rt Linux Micro 6.2 6.12.0-160000.37.1
  • kernel-64kb SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-source SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-default-base SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1.160000.2.19
  • kernel-syms SLES 16.0, Linux Micro Extras 6.2, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-azure SLES 16.0, SLES for SAP applications 16.0 6.12.0-160000.37.1
  • kernel-obs-qa SLES 16.0, SLES for SAP applications 16.0 6.12.0-160000.37.1

suse advisories SUSE-SU-2026:23237-1SUSE-SU-2026:23068-1SUSE-SU-2026:23221-1SUSE-SU-2026:23231-1SUSE-SU-2026:23066-1SUSE-SU-2026:2799-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.37.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.37.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.37.1

opensuse advisories openSUSE-SU-2026:21555-1openSUSE-SU-2026:10954-1

  • kernel AlmaLinux 10 6.12.0-211.53.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.53.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.53.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.53.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.53.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.53.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.53.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.53.1.el10_2

almalinux advisories ALSA-2026:65334

  • kernel Rocky Linux 10 6.12.0-211.53.1.el10_2

rocky linux advisories RLSA-2026:65334

  • kernel Azure Linux 3.0 6.6.141.1-1

azure linux advisories AZL-89096

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-46123 updated cvss 6.2

kernel: Bluetooth: virtio_bt: clamp rx length before skb_put

  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.53.1.el10_2, perf 6.12.0-211.53.1.el10_2, rtla 6.12.0-211.53.1.el10_2, python3-perf 6.12.0-211.53.1.el10_2, kernel-devel-matched 6.12.0-211.53.1.el10_2, kernel-64k-devel-matched 6.12.0-211.53.1.el10_2, +7 more Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.53.1.el10_2, kernel-64k 6.12.0-211.53.1.el10_2, kernel-core 6.12.0-211.53.1.el10_2, kernel-tools 6.12.0-211.53.1.el10_2, kernel-modules 6.12.0-211.53.1.el10_2, kernel-64k-core 6.12.0-211.53.1.el10_2, +28 more Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.53.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.53.1.el10_2 Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.53.1.el10_2, kernel-rt-64k 6.12.0-211.53.1.el10_2, kernel-rt-core 6.12.0-211.53.1.el10_2, kernel-rt-modules 6.12.0-211.53.1.el10_2, kernel-rt-64k-core 6.12.0-211.53.1.el10_2, kernel-rt-debug-core 6.12.0-211.53.1.el10_2, +14 more Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.53.1.el10_2, kernel-rt-core 6.12.0-211.53.1.el10_2, kernel-rt-modules 6.12.0-211.53.1.el10_2, kernel-rt-debug-core 6.12.0-211.53.1.el10_2, kernel-rt-modules-core 6.12.0-211.53.1.el10_2, kernel-rt-debug-modules 6.12.0-211.53.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:65334
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.