medium 5.5

CVE-2021-3564 json

A flaw double-free memory corruption in the Linux kernel HCI device initialization subsystem was found in the way user attach malicious HCI…

published 2021-06-08 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26874

cvss: 5.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.5%; EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits: 0; none known

A flaw double-free memory corruption in the Linux kernel HCI device initialization subsystem was found in the way user attach malicious HCI TTY Bluetooth device. A local user could use this flaw to crash the system. This flaw affects all the Linux kernel versions starting from 3.13.

Patch / fix

distros 7

debian ubuntu red hat suse opensuse azure linux arch linux

linux Debian 14, Debian 13, Debian 12 5.10.46-1

debian advisories DEBIAN-CVE-2021-3564

linux Ubuntu 18.04 LTS 4.15.0-154.161
linux Ubuntu 20.04 LTS 5.4.0-81.91
linux-aws Ubuntu 18.04 LTS 4.15.0-1110.117
linux-aws Ubuntu 20.04 LTS 5.4.0-1055.58
linux-gcp Ubuntu 20.04 LTS 5.4.0-1051.55
linux-gke Ubuntu 20.04 LTS 5.4.0-1051.54
linux-kvm Ubuntu 18.04 LTS 4.15.0-1098.100
linux-kvm Ubuntu 20.04 LTS 5.4.0-1045.47

ubuntu advisories UBUNTU-CVE-2021-3564

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 8 4.18.0-348.el8
perf RHEL 8 4.18.0-348.el8
bpftool RHEL 8 4.18.0-348.el8
kernel-core RHEL 8 4.18.0-348.el8
kernel-tools RHEL 8 4.18.0-348.el8
python3-perf RHEL 8 4.18.0-348.el8
kernel-modules RHEL 8 4.18.0-348.el8
kernel-zfcpdump RHEL 8 4.18.0-348.el8

red hat advisories RHSA-2021:4356 RHSA-2022:0622 RHSA-2022:0620 RHSA-2021:4140

kernel-rt SLE Real Time 12 SP5 4.12.14-10.78.1
kernel-syms-rt SLE Real Time 12 SP5 4.12.14-10.78.1
kernel-rt_debug SLE Real Time 12 SP5 4.12.14-10.78.1
kernel-source-rt SLE Real Time 12 SP5 4.12.14-10.78.1
kernel-syms SLES 12 SP2-BCL 4.4.121-92.164.1
kernel-source SLES 12 SP2-BCL 4.4.121-92.164.1
kernel-default SLES 12 SP2-BCL 4.4.121-92.164.1
kernel-azure SLES for SAP 12 SP5, SLES 12 SP5 4.12.14-16.88.1

suse advisories SUSE-SU-2022:0555-1 SUSE-SU-2022:0477-1 SUSE-SU-2022:0372-1 SUSE-SU-2022:0371-1 SUSE-SU-2022:0367-1 SUSE-SU-2022:0366-1

kernel-default openSUSE Leap 15.3 4.12.14-197.105.1
kernel-vanilla openSUSE Leap 15.3 4.12.14-197.105.1
kernel-kvmsmall openSUSE Leap 15.3 4.12.14-197.105.1
kernel-zfcpdump openSUSE Leap 15.3 4.12.14-197.105.1

opensuse advisories openSUSE-SU-2022:0366-1

kernel Azure Linux 3.0 6.6.35.1-4
kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-34858 AZL-6573

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

linux Arch Linux 5.12.10.arch1-1
linux-zen Arch Linux 5.12.10.zen1-1
linux-hardened Arch Linux 5.12.10.hardened1-1
linux-lts Arch Linux 5.10.43-1

arch linux advisories AVG-2063 AVG-2064 AVG-2065 AVG-2066

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-2021-3564 updated 2026-11-07 cvss 6.3

kernel: double free in bluetooth subsystem when the HCI device initialization fails

Red Hat Enterprise Linux 7 perf, kernel, kernel-alt, python-perf, kernel-kdump, kernel-tools, +3 more
affected: workaround, no fix planned “Out of support scope”
Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-348.el8, kernel-debuginfo-common-aarch64 4.18.0-348.el8, kernel-debuginfo-common-ppc64le 4.18.0-348.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-348.el8, kernel 4.18.0-348.el8, bpftool 4.18.0-348.el8, kernel-core 4.18.0-348.el8, kernel-tools 4.18.0-348.el8, python3-perf 4.18.0-348.el8, +15 more
fixed: vendor fix RHSA-2021:4356
Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-1160.59.1.el7, kernel 3.10.0-1160.59.1.el7, bpftool 3.10.0-1160.59.1.el7, python-perf 3.10.0-1160.59.1.el7, kernel-tools 3.10.0-1160.59.1.el7, kernel-tools-libs 3.10.0-1160.59.1.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7
fixed: vendor fix RHSA-2022:0620
Red Hat Enterprise Linux for Real Time (v. 7) kernel-rt 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-trace 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.59.1.rt56.1200.el7 Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-kvm 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-trace 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-debug-kvm 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-trace-kvm 3.10.0-1160.59.1.rt56.1200.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.59.1.rt56.1200.el7
fixed: vendor fix RHSA-2022:0622
Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-348.rt7.130.el8, kernel-rt-core 4.18.0-348.rt7.130.el8, kernel-rt-modules 4.18.0-348.rt7.130.el8, kernel-rt-debug-core 4.18.0-348.rt7.130.el8, kernel-rt-debug-modules 4.18.0-348.rt7.130.el8, kernel-rt-modules-extra 4.18.0-348.rt7.130.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-348.rt7.130.el8, kernel-rt-kvm 4.18.0-348.rt7.130.el8, kernel-rt-core 4.18.0-348.rt7.130.el8, kernel-rt-modules 4.18.0-348.rt7.130.el8, kernel-rt-debug-kvm 4.18.0-348.rt7.130.el8, kernel-rt-debug-core 4.18.0-348.rt7.130.el8, +4 more
fixed: vendor fix RHSA-2021:4140
Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-1160.59.1.el7, kernel 3.10.0-1160.59.1.el7, bpftool 3.10.0-1160.59.1.el7, python-perf 3.10.0-1160.59.1.el7, kernel-kdump 3.10.0-1160.59.1.el7, kernel-tools 3.10.0-1160.59.1.el7, +7 more Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-1160.59.1.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.59.1.el7 Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-1160.59.1.el7, kernel 3.10.0-1160.59.1.el7, bpftool 3.10.0-1160.59.1.el7, python-perf 3.10.0-1160.59.1.el7, kernel-tools 3.10.0-1160.59.1.el7, kernel-tools-libs 3.10.0-1160.59.1.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.59.1.el7
fixed: vendor fix RHSA-2022:0620
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 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

0.48% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

openwall.com http://www.openwall.com/lists/oss-security/2021/05/25/1 referenced PoC, tagged "exploit" by a source, unverified
openwall.com http://www.openwall.com/lists/oss-security/2021/06/01/2 referenced PoC, tagged "exploit" by a source, unverified
openwall.com https://www.openwall.com/lists/oss-security/2021/05/25/1 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	2.1	AV:L/AC:L/Au:N/C:N/I:N/A:P

Affected products

n/a kernel

Classification

Weakness

CWE-415 Double Free

Technology feeds

Linux kernel rss critical rss

References

openwall.com /lists/oss-security/2021/05/25/1
mailing-list, exploit, third-party-advisory
openwall.com /lists/oss-security/2021/06/01/2
mailing-list, exploit
openwall.com /lists/oss-security/2021/05/25/1
exploit, mailing-list, third-party-advisory
bugzilla.redhat.com /show_bug.cgi?id=1964139
issue-tracking, third-party-advisory
lists.debian.org /debian-lts-announce/2021/06/msg00020.html
mailing-list, third-party-advisory
lists.debian.org /debian-lts-announce/2021/06/msg00019.html
mailing-list, third-party-advisory

Sources

CVE List CVE-2021-3564
NVD CVE-2021-3564

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.

Summary