Skip to content
Fencer Vulns
high 7.8

CVE-2026-31772 json

Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync

published 2026-05-01 6 mo ago modified 2026-10-19 20 d ago also EUVD-2026-26585

cvss
7.8
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: hci_sync: fix stack buffer overflow in hci_le_big_create_sync

hci_le_big_create_sync() uses DEFINE_FLEX to allocate a struct hci_cp_le_big_create_sync on the stack with room for 0x11 (17) BIS entries. However, conn->num_bis can hold up to HCI_MAX_ISO_BIS (31) entries — validated against ISO_MAX_NUM_BIS (0x1f) in the caller hci_conn_big_create_sync(). When conn->num_bis is between 18 and 31, the memcpy that copies conn->bis into cp->bis writes up to 14 bytes past the stack buffer, corrupting adjacent stack memory.

This is trivially reproducible: binding an ISO socket with bc_num_bis = ISO_MAX_NUM_BIS (31) and calling listen() will eventually trigger hci_le_big_create_sync() from the HCI command sync worker, causing a KASAN-detectable stack-out-of-bounds write:

BUG: KASAN: stack-out-of-bounds in hci_le_big_create_sync+0x256/0x3b0 Write of size 31 at addr ffffc90000487b48 by task kworker/u9:0/71

Fix this by changing the DEFINE_FLEX count from the incorrect 0x11 to HCI_MAX_ISO_BIS, which matches the maximum number of BIS entries that conn->bis can actually carry.

Patch / fix

  • Linux Linux 6.12, 6.12.81, 6.18.22, 6.19.12, 7.0
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.19.12-1

debian advisories DEBIAN-CVE-2026-31772

  • linux Ubuntu 24.04 LTS 6.8.0-136.136
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1059.67
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1061.62
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1063.71
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1046.50
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1061.65

ubuntu advisories UBUNTU-CVE-2026-31772

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 9 5.14.0-687.17.1.el9_8
  • rv RHEL 9 5.14.0-687.17.1.el9_8
  • perf RHEL 9 5.14.0-687.17.1.el9_8
  • rtla RHEL 9 5.14.0-687.17.1.el9_8
  • libperf RHEL 9 5.14.0-687.17.1.el9_8
  • kernel-rt RHEL 9 5.14.0-687.17.1.el9_8
  • kernel-64k RHEL 9 5.14.0-687.17.1.el9_8
  • kernel-core RHEL 9 5.14.0-687.17.1.el9_8

red hat advisories RHSA-2026:83707RHSA-2026:27789RHSA-2026:27288

  • 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-2026:23066-1

  • 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-2026:21555-1

  • kernel AlmaLinux 9 5.14.0-687.17.1.el9_8
  • rv AlmaLinux 9 5.14.0-687.17.1.el9_8
  • perf AlmaLinux 9 5.14.0-687.17.1.el9_8
  • rtla AlmaLinux 9 5.14.0-687.17.1.el9_8
  • libperf AlmaLinux 9 5.14.0-687.17.1.el9_8
  • kernel-rt AlmaLinux 9 5.14.0-687.17.1.el9_8
  • kernel-64k AlmaLinux 9 5.14.0-687.17.1.el9_8
  • kernel-core AlmaLinux 9 5.14.0-687.17.1.el9_8

almalinux advisories ALSA-2026:27789ALSA-2026:27288

  • kernel Rocky Linux 9 5.14.0-687.17.1.el9_8
  • kernel Rocky Linux 10 6.12.0-211.26.1.el10_2

rocky linux advisories RLSA-2026:27789RLSA-2026:27288

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-2026-31772 updated cvss 7.0

kernel: Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync

  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.17.1.el9_8, perf 5.14.0-687.17.1.el9_8, rtla 5.14.0-687.17.1.el9_8, python3-perf 5.14.0-687.17.1.el9_8, kernel-devel-matched 5.14.0-687.17.1.el9_8, kernel-64k-devel-matched 5.14.0-687.17.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:27789
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.26.1.el10_2, perf 6.12.0-211.26.1.el10_2, rtla 6.12.0-211.26.1.el10_2, python3-perf 6.12.0-211.26.1.el10_2, kernel-devel-matched 6.12.0-211.26.1.el10_2, kernel-64k-devel-matched 6.12.0-211.26.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:27288
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) rv 6.12.0-55.111.1.el10_0, perf 6.12.0-55.111.1.el10_0, rtla 6.12.0-55.111.1.el10_0, python3-perf 6.12.0-55.111.1.el10_0, kernel-devel-matched 6.12.0-55.111.1.el10_0, kernel-64k-devel-matched 6.12.0-55.111.1.el10_0, +7 more
    fixed: vendor fix RHSA-2026:83707
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.17.1.el9_8, kernel-64k 5.14.0-687.17.1.el9_8, kernel-core 5.14.0-687.17.1.el9_8, kernel-tools 5.14.0-687.17.1.el9_8, kernel-modules 5.14.0-687.17.1.el9_8, kernel-64k-core 5.14.0-687.17.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:27789
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.26.1.el10_2, kernel-64k 6.12.0-211.26.1.el10_2, kernel-core 6.12.0-211.26.1.el10_2, kernel-tools 6.12.0-211.26.1.el10_2, kernel-modules 6.12.0-211.26.1.el10_2, kernel-64k-core 6.12.0-211.26.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:27288
  • Red Hat Enterprise Linux BaseOS EUS (v. 10.0) kernel 6.12.0-55.111.1.el10_0, kernel-64k 6.12.0-55.111.1.el10_0, kernel-core 6.12.0-55.111.1.el10_0, kernel-tools 6.12.0-55.111.1.el10_0, kernel-modules 6.12.0-55.111.1.el10_0, kernel-64k-core 6.12.0-55.111.1.el10_0, +27 more
    fixed: vendor fix RHSA-2026:83707
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.17.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.17.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.17.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.17.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.17.1.el9_8
    fixed: vendor fix RHSA-2026:27789
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.26.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.26.1.el10_2
    fixed: vendor fix RHSA-2026:27288
show 8 more
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) libperf 6.12.0-55.111.1.el10_0, kernel-debuginfo-common-s390x 6.12.0-55.111.1.el10_0, kernel-debuginfo-common-x86_64 6.12.0-55.111.1.el10_0, kernel-debuginfo-common-aarch64 6.12.0-55.111.1.el10_0, kernel-debuginfo-common-ppc64le 6.12.0-55.111.1.el10_0
    fixed: vendor fix RHSA-2026:83707
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.17.1.el9_8, kernel-rt-64k 5.14.0-687.17.1.el9_8, kernel-rt-core 5.14.0-687.17.1.el9_8, kernel-rt-modules 5.14.0-687.17.1.el9_8, kernel-rt-64k-core 5.14.0-687.17.1.el9_8, kernel-rt-debug-core 5.14.0-687.17.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:27789
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.26.1.el10_2, kernel-rt-64k 6.12.0-211.26.1.el10_2, kernel-rt-core 6.12.0-211.26.1.el10_2, kernel-rt-modules 6.12.0-211.26.1.el10_2, kernel-rt-64k-core 6.12.0-211.26.1.el10_2, kernel-rt-debug-core 6.12.0-211.26.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:27288
  • Red Hat Enterprise Linux Real Time EUS (v. 10.0) kernel-rt 6.12.0-55.111.1.el10_0, kernel-rt-64k 6.12.0-55.111.1.el10_0, kernel-rt-core 6.12.0-55.111.1.el10_0, kernel-rt-modules 6.12.0-55.111.1.el10_0, kernel-rt-64k-core 6.12.0-55.111.1.el10_0, kernel-rt-debug-core 6.12.0-55.111.1.el10_0, +14 more
    fixed: vendor fix RHSA-2026:83707
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.17.1.el9_8, kernel-rt-core 5.14.0-687.17.1.el9_8, kernel-rt-modules 5.14.0-687.17.1.el9_8, kernel-rt-debug-core 5.14.0-687.17.1.el9_8, kernel-rt-modules-core 5.14.0-687.17.1.el9_8, kernel-rt-debug-modules 5.14.0-687.17.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:27789
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.26.1.el10_2, kernel-rt-core 6.12.0-211.26.1.el10_2, kernel-rt-modules 6.12.0-211.26.1.el10_2, kernel-rt-debug-core 6.12.0-211.26.1.el10_2, kernel-rt-modules-core 6.12.0-211.26.1.el10_2, kernel-rt-debug-modules 6.12.0-211.26.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:27288
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0) kernel-rt 6.12.0-55.111.1.el10_0, kernel-rt-kvm 6.12.0-55.111.1.el10_0, kernel-rt-core 6.12.0-55.111.1.el10_0, kernel-rt-modules 6.12.0-55.111.1.el10_0, kernel-rt-debug-kvm 6.12.0-55.111.1.el10_0, kernel-rt-debug-core 6.12.0-55.111.1.el10_0, +6 more
    fixed: vendor fix RHSA-2026:83707
  • 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 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns 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.