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Fencer Intel
medium 6.4

CVE-2021-3573 json

A use-after-free in function hci_sock_bound_ioctl() of the Linux kernel HCI subsystem was found in the way user calls ioct HCIUNBLOCKADDR o…

published 5y ago modified 4mo ago also EUVD-2021-26882

cvss
6.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

A use-after-free in function hci_sock_bound_ioctl() of the Linux kernel HCI subsystem was found in the way user calls ioct HCIUNBLOCKADDR or other way triggers race condition of the call hci_unregister_dev() together with one of the calls hci_sock_blacklist_add(), hci_sock_blacklist_del(), hci_get_conn_info(), hci_get_auth_info(). A privileged local user could use this flaw to crash the system or escalate their privileges on the system. This flaw affects the Linux kernel versions prior to 5.13-rc5.

Patch / fix

  • linux linux_kernel 5.13
  • linux Debian 14, Debian 13, Debian 12 5.10.46-1

debian advisories DEBIAN-CVE-2021-3573

  • 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-2021-3573

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-2021:4356RHSA-2022:0622RHSA-2022:0620RHSA-2021:4140

  • kernel-rt Real Time Module 15 SP2 5.3.18-42.2
  • oracleasm Real Time Module 15 SP2 2.0.8-1.3.1
  • lttng-modules Real Time Module 15 SP2 2.10.10-1.5.1
  • kernel-syms-rt Real Time Module 15 SP2 5.3.18-42.1
  • kernel-rt_debug Real Time Module 15 SP2 5.3.18-42.2
  • kernel-source-rt Real Time Module 15 SP2 5.3.18-42.1
  • kernel-64kb SLE Module for Basesystem 15 SP3 5.3.18-59.13.1
  • kernel-syms SLE Module for Development Tools 15 SP3 5.3.18-59.13.1

suse advisories SUSE-SU-2021:3459-1SUSE-SU-2021:3443-1SUSE-SU-2021:3440-1SUSE-SU-2021:3401-1SUSE-SU-2021:3371-1SUSE-SU-2021:3360-1

  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-source openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-default openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-preempt openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-kvmsmall openSUSE Leap 15.3 5.3.18-59.13.1
  • kernel-zfcpdump openSUSE Leap 15.3 5.3.18-59.13.1

opensuse advisories openSUSE-SU-2021:2352-1openSUSE-SU-2021:2305-1

  • kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6574

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-2063AVG-2064AVG-2065AVG-2066

Is CVE-2021-3573 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2021-3573 updated cvss 6.7

kernel: use-after-free in function hci_sock_bound_ioctl()

  • 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

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • openwall.com https://www.openwall.com/lists/oss-security/2021/06/08/2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.4 CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Affected products

  • n/a kernel

Classification

Weakness
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
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.