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Fencer Vulns
high 8.8

CVE-2021-47520 json

can: pch_can: pch_can_rx_normal: fix use after free

published 2024-05-24 2 y ago modified 2026-08-05 3 mo ago also EUVD-2021-34524

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

can: pch_can: pch_can_rx_normal: fix use after free

After calling netif_receive_skb(skb), dereferencing skb is unsafe. Especially, the can_frame cf which aliases skb memory is dereferenced just after the call netif_receive_skb(skb).

Reordering the lines solves the issue.

Patch / fix

  • Linux Linux 4.4.295, 4.9.293, 4.14.258, 4.19.221, 5.4.165, 5.10.85, 5.15.8, 5.16
  • linux Debian 14, Debian 13, Debian 12 5.15.15-1

debian advisories DEBIAN-CVE-2021-47520

  • linux Ubuntu 18.04 LTS 4.15.0-169.177
  • linux Ubuntu 20.04 LTS 5.4.0-100.113
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1121.129
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1066.69
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1065.69
  • linux-ibm Ubuntu 20.04 LTS 5.4.0-1015.16
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1107.109
  • linux-kvm Ubuntu 20.04 LTS 5.4.0-1056.58

ubuntu advisories UBUNTU-CVE-2021-47520

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-64kb SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS, Enterprise Storage 7.1 5.3.18-150300.59.170.1
  • kernel-syms SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.170.1
  • kernel-source SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.170.1
  • kernel-default SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +5 more 5.3.18-150300.59.170.1
  • kernel-preempt SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.170.1
  • kernel-obs-build SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.170.1
  • kernel-default-base SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +3 more 5.3.18-150300.59.170.1.150300.18.100.1
  • kernel-default SLES for SAP 15 SP2, SLES 15 SP2-LTSS, SLE Live Patching 15 SP2 +2 more 5.3.18-150200.24.200.1

suse advisories SUSE-SU-2024:2948-1SUSE-SU-2024:2923-1SUSE-SU-2024:2901-1SUSE-SU-2024:2895-1SUSE-SU-2024:2893-1SUSE-SU-2024:2561-1

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-2021-47520 updated cvss 6.8

kernel: can: pch_can: pch_can_rx_normal: fix use after free

  • 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

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 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.