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Fencer Vulns
high 7.8

CVE-2021-3715 json

A flaw was found in the "Routing decision" classifier in the Linux kernel's Traffic Control networking subsystem in the way it handled chan…

published 2022-03-02 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-26996

cvss
7.8
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 29%
public exploits
0
none known

Summary

A flaw was found in the "Routing decision" classifier in the Linux kernel's Traffic Control networking subsystem in the way it handled changing of classification filters, leading to a use-after-free condition. This flaw allows unprivileged local users to escalate their privileges on the system. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability.

Patch / fix

  • linux linux_kernel 4.4.218, 4.9.218, 4.14.175, 4.19.114, 5.4.29, 5.5.14
  • linux Debian 14, Debian 13, Debian 12 5.5.17-1

debian advisories DEBIAN-CVE-2021-3715

  • linux Ubuntu 16.04 LTS 4.4.0-179.209
  • linux Ubuntu 18.04 LTS 4.15.0-99.100
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1107.118
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1066.70
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1061.65
  • linux-hwe Ubuntu 16.04 LTS 4.15.0-99.100~16.04.1
  • linux-kvm Ubuntu 16.04 LTS 4.4.0-1071.78
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1059.60

ubuntu advisories UBUNTU-CVE-2021-3715

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 4.18.0-240.el8
  • perf RHEL 8 4.18.0-240.el8
  • bpftool RHEL 8 4.18.0-240.el8
  • kernel-core RHEL 8 4.18.0-240.el8
  • kernel-tools RHEL 8 4.18.0-240.el8
  • python3-perf RHEL 8 4.18.0-240.el8
  • kernel-modules RHEL 8 4.18.0-240.el8
  • kernel-zfcpdump RHEL 8 4.18.0-240.el8

red hat advisories RHSA-2021:3443RHSA-2021:3442RHSA-2021:3446RHSA-2021:3444RHSA-2020:4431RHSA-2022:7173

  • kernel-syms SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.83.2
  • kernel-source SLES for SAP 12 SP4, SLES 12 SP4-LTSS, OpenStack Cloud Crowbar 9 +1 more 4.12.14-95.83.2
  • kernel-default SLES for SAP 12 SP4, SLES 12 SP4-LTSS, SLE Live Patching 12 SP4 +3 more 4.12.14-95.83.2
  • kernel-syms SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.4.180-94.150.1
  • kernel-source SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +3 more 4.4.180-94.150.1
  • kernel-default SLES for SAP 12 SP3, SLES 12 SP3-LTSS, SLES 12 SP3-BCL +4 more 4.4.180-94.150.1
  • kgraft-patch-SLE12-SP3_Update_41 SLES for SAP 12 SP3, SLES 12 SP3-LTSS, OpenStack Cloud Crowbar 8 +2 more 1-4.3.1
  • kernel-syms SLES 12 SP2-BCL 4.4.121-92.161.1

suse advisories SUSE-SU-2021:3972-1SUSE-SU-2021:3935-1SUSE-SU-2021:3929-1SUSE-SU-2021:3876-1SUSE-SU-2021:3754-1SUSE-SU-2021:3748-1

  • kernel-default openSUSE Leap 15.3 4.12.14-197.102.2
  • kernel-vanilla openSUSE Leap 15.3 4.12.14-197.102.2
  • kernel-kvmsmall openSUSE Leap 15.3 4.12.14-197.102.2
  • kernel-zfcpdump openSUSE Leap 15.3 4.12.14-197.102.2
  • dtb-aarch64 openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-64kb openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-syms openSUSE Leap 15.3 5.3.18-59.34.1
  • kernel-obs-qa openSUSE Leap 15.3 5.3.18-59.34.1

opensuse advisories openSUSE-SU-2021:3876-1openSUSE-SU-2021:3675-1openSUSE-SU-2021:1477-1openSUSE-SU-2021:3641-1

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-2021-3715 updated cvss 7.8

kernel: use-after-free in route4_change() in net/sched/cls_route.c

  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, python-perf, kernel-kdump, kernel-tools, kernel-tools-libs, +2 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-240.el8, kernel-debuginfo-common-aarch64 4.18.0-240.el8, kernel-debuginfo-common-ppc64le 4.18.0-240.el8
    fixed: vendor fix RHSA-2020:4431
  • Red Hat CodeReady Linux Builder EUS (v. 8.1) kernel-debuginfo-common-x86_64 4.18.0-147.54.2.el8_1, kernel-debuginfo-common-aarch64 4.18.0-147.54.2.el8_1, kernel-debuginfo-common-ppc64le 4.18.0-147.54.2.el8_1
    fixed: vendor fix RHSA-2021:3444
  • Red Hat CodeReady Linux Builder EUS (v. 8.2) kernel-debuginfo-common-x86_64 4.18.0-193.65.2.el8_2, kernel-debuginfo-common-aarch64 4.18.0-193.65.2.el8_2, kernel-debuginfo-common-ppc64le 4.18.0-193.65.2.el8_2
    fixed: vendor fix RHSA-2021:3446
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-240.el8, kernel 4.18.0-240.el8, bpftool 4.18.0-240.el8, kernel-core 4.18.0-240.el8, kernel-tools 4.18.0-240.el8, python3-perf 4.18.0-240.el8, +15 more
    fixed: vendor fix RHSA-2020:4431
  • Red Hat Enterprise Linux BaseOS EUS (v. 8.1) perf 4.18.0-147.54.2.el8_1, kernel 4.18.0-147.54.2.el8_1, bpftool 4.18.0-147.54.2.el8_1, kernel-core 4.18.0-147.54.2.el8_1, kernel-tools 4.18.0-147.54.2.el8_1, python3-perf 4.18.0-147.54.2.el8_1, +25 more
    fixed: vendor fix RHSA-2021:3444
  • Red Hat Enterprise Linux BaseOS EUS (v. 8.2) perf 4.18.0-193.65.2.el8_2, kernel 4.18.0-193.65.2.el8_2, bpftool 4.18.0-193.65.2.el8_2, kernel-core 4.18.0-193.65.2.el8_2, kernel-tools 4.18.0-193.65.2.el8_2, python3-perf 4.18.0-193.65.2.el8_2, +27 more
    fixed: vendor fix RHSA-2021:3446
  • Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-1160.42.2.el7, kernel 3.10.0-1160.42.2.el7, bpftool 3.10.0-1160.42.2.el7, python-perf 3.10.0-1160.42.2.el7, kernel-tools 3.10.0-1160.42.2.el7, kernel-tools-libs 3.10.0-1160.42.2.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.42.2.el7 Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.42.2.el7
    fixed: vendor fix RHSA-2021:3438
show 10 more
  • Red Hat Enterprise Linux for Real Time (v. 7) kernel-rt 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-trace 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.42.2.rt56.1182.el7 Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-kvm 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-trace 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-debug-kvm 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-trace-kvm 3.10.0-1160.42.2.rt56.1182.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.42.2.rt56.1182.el7
    fixed: vendor fix RHSA-2021:3439
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-240.rt7.54.el8, kernel-rt-core 4.18.0-240.rt7.54.el8, kernel-rt-modules 4.18.0-240.rt7.54.el8, kernel-rt-debug-core 4.18.0-240.rt7.54.el8, kernel-rt-debug-modules 4.18.0-240.rt7.54.el8, kernel-rt-modules-extra 4.18.0-240.rt7.54.el8, +2 more
    fixed: vendor fix RHSA-2020:4609
  • Red Hat Enterprise Linux Real Time EUS (v. 8.2) kernel-rt 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-core 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-modules 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-debug-core 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-debug-modules 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-modules-extra 4.18.0-193.65.2.rt13.117.el8_2, +2 more
    fixed: vendor fix RHSA-2021:3445
  • Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-240.rt7.54.el8, kernel-rt-kvm 4.18.0-240.rt7.54.el8, kernel-rt-core 4.18.0-240.rt7.54.el8, kernel-rt-modules 4.18.0-240.rt7.54.el8, kernel-rt-debug-kvm 4.18.0-240.rt7.54.el8, kernel-rt-debug-core 4.18.0-240.rt7.54.el8, +4 more
    fixed: vendor fix RHSA-2020:4609
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 8.2) kernel-rt 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-kvm 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-core 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-modules 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-debug-kvm 4.18.0-193.65.2.rt13.117.el8_2, kernel-rt-debug-core 4.18.0-193.65.2.rt13.117.el8_2, +4 more
    fixed: vendor fix RHSA-2021:3445
  • Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-1160.42.2.el7, kernel 3.10.0-1160.42.2.el7, bpftool 3.10.0-1160.42.2.el7, kpatch-patch-3_10_0-1160 1-9.el7, python-perf 3.10.0-1160.42.2.el7, kernel-kdump 3.10.0-1160.42.2.el7, +19 more
    fixed: vendor fix RHSA-2021:3438
  • Red Hat Enterprise Linux Server E4S (v. 7.6) kpatch-patch-3_10_0-957_84_1 1-6.el7, kpatch-patch-3_10_0-957_92_1 1-3.el7, kpatch-patch-3_10_0-957_94_1 1-2.el7, kpatch-patch-3_10_0-957_95_1 1-1.el7, kpatch-patch-3_10_0-957_97_1 1-1.el7
    fixed: vendor fix RHSA-2022:7173
  • Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-1160.42.2.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.42.2.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.42.2.el7 Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-1160.42.2.el7, kernel 3.10.0-1160.42.2.el7, bpftool 3.10.0-1160.42.2.el7, python-perf 3.10.0-1160.42.2.el7, kernel-tools 3.10.0-1160.42.2.el7, kernel-tools-libs 3.10.0-1160.42.2.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.42.2.el7
    fixed: vendor fix RHSA-2021:3438
  • Red Hat Virtualization 4 Hypervisor for RHEL 7 redhat-virtualization-host 4.3.18-20210903.0.el7_9, redhat-virtualization-host-image-update 4.3.18-20210903.0.el7_9 Red Hat RHEL 7-based RHEV-H for RHEV 4 (build requirements) redhat-virtualization-host 4.3.18-20210903.0.el7_9, redhat-virtualization-host-image-update 4.3.18-20210903.0.el7_9
    fixed: vendor fix RHSA-2021:3477
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +82 more Red Hat RHEL 7-based RHEV-H for RHEV 4 (build requirements) redhat-release-virtualization-host 4.3.18-1.el7ev, redhat-virtualization-host-image-update-placeholder 4.3.18-1.el7ev
    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

0.35% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a kernel

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.