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Fencer Intel
medium 5.5

CVE-2021-34693 json

net/can/bcm.c in the Linux kernel through 5.12.10 allows local users to obtain sensitive information from kernel stack memory because parts…

published 5y ago modified last mo. also EUVD-2021-21343

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 41%
public exploits
0
none known

Summary

net/can/bcm.c in the Linux kernel through 5.12.10 allows local users to obtain sensitive information from kernel stack memory because parts of a data structure are uninitialized.

Patch / fix

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

debian advisories DEBIAN-CVE-2021-34693

  • linux Ubuntu 18.04 LTS 4.15.0-156.163
  • linux Ubuntu 20.04 LTS 5.4.0-81.91
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1111.118
  • 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 4.15.0-1099.101
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1045.47

ubuntu advisories UBUNTU-CVE-2021-34693

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-syms SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.4.180-94.147.1
  • kernel-source SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.4.180-94.147.1
  • kernel-default SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +4 more 4.4.180-94.147.1
  • kgraft-patch-SLE12-SP3_Update_40 SLES for SAP 12 SP3, SLES 12 SP3-LTSS, OpenStack Cloud Crowbar 8 +2 more 1-4.3.1
  • kernel-syms SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 4.12.14-197.99.1
  • kernel-source SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +6 more 4.12.14-197.99.1
  • kernel-default SLES for SAP 15 SP1, SLES 15 SP1-LTSS, SLES 15 SP1-BCL +8 more 4.12.14-197.99.1
  • kernel-zfcpdump SLES 15 SP1-LTSS, Manager Server 4.0 4.12.14-197.99.1

suse advisories SUSE-SU-2021:2451-1SUSE-SU-2021:2427-1SUSE-SU-2021:2426-1SUSE-SU-2021:2422-1SUSE-SU-2021:2421-1SUSE-SU-2021:2406-1

  • kernel-default openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-vanilla openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-kvmsmall openSUSE Leap 15.3 4.12.14-197.99.1
  • kernel-zfcpdump openSUSE Leap 15.3 4.12.14-197.99.1
  • 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

opensuse advisories openSUSE-SU-2021:2427-1openSUSE-SU-2021:2352-1openSUSE-SU-2021:2305-1

  • kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6567

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 5.12.13.arch1-1
  • linux-zen Arch Linux 5.12.13.zen1-1
  • linux-hardened Arch Linux 5.12.13.hardened1-1
  • linux-lts Arch Linux 5.10.46-1

arch linux advisories AVG-2094AVG-2095AVG-2096AVG-2097

Is CVE-2021-34693 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.

Check with Fencer

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-2021-34693 updated cvss 4.0

kernel: allows local users to obtain sensitive information from stack memory because of uninitialized data structure in net/can/bcm.c

  • 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, kernel-alt, python-perf, +9 more
    affected: workaround, no fix planned “Out of support scope”
  • 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, +81 more
    affected: workaround, no fix available

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
partial
Assessed
last mo.

Exploit prediction

0.47% chance of exploitation in the next 30 days, higher than 41% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • openwall.com http://www.openwall.com/lists/oss-security/2021/06/15/1 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:H/I:N/A:N
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness
  • CWE-909 Missing Initialization of Resource
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.