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Fencer Vulns
medium 5.5

CVE-2021-33630 json

NULL-ptr-deref in network sched

published 2024-01-18 2 y ago modified 2026-06-17 4 mo ago also EUVD-2021-20307

cvss
5.5
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

NULL Pointer Dereference vulnerability in openEuler kernel on Linux (network modules) allows Pointer Manipulation. This vulnerability is associated with program files net/sched/sch_cbs.C.

This issue affects openEuler kernel: from 4.19.90 before 4.19.90-2401.3.

Patch / fix

  • openatom openeuler 4.19.90-2401.3
  • linux Debian 14, Debian 13, Debian 12 5.3.7-1

debian advisories DEBIAN-CVE-2021-33630

  • linux-hwe-edge Ubuntu 18.04 LTS 5.3.0-22.24~18.04.1

ubuntu advisories UBUNTU-CVE-2021-33630

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-rt RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-kvm RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-core RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-modules RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-debug-kvm RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-debug-core RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-debug-modules RHEL 8 4.18.0-193.rt13.51.el8
  • kernel-rt-modules-extra RHEL 8 4.18.0-193.rt13.51.el8

red hat advisories RHSA-2020:1567RHSA-2020:1769

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-2021-33630 updated cvss 5.5

kernel: net/sched: cbs NULL pointer dereference when offloading is enabled

  • 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
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-193.el8, kernel-debuginfo-common-aarch64 4.18.0-193.el8, kernel-debuginfo-common-ppc64le 4.18.0-193.el8 Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-193.el8, kernel 4.18.0-193.el8, bpftool 4.18.0-193.el8, kernel-core 4.18.0-193.el8, kernel-tools 4.18.0-193.el8, python3-perf 4.18.0-193.el8, +15 more
    fixed: vendor fix RHSA-2020:1769
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-193.rt13.51.el8, kernel-rt-core 4.18.0-193.rt13.51.el8, kernel-rt-modules 4.18.0-193.rt13.51.el8, kernel-rt-debug-core 4.18.0-193.rt13.51.el8, kernel-rt-debug-modules 4.18.0-193.rt13.51.el8, kernel-rt-modules-extra 4.18.0-193.rt13.51.el8, +2 more Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-193.rt13.51.el8, kernel-rt-kvm 4.18.0-193.rt13.51.el8, kernel-rt-core 4.18.0-193.rt13.51.el8, kernel-rt-modules 4.18.0-193.rt13.51.el8, kernel-rt-debug-kvm 4.18.0-193.rt13.51.el8, kernel-rt-debug-core 4.18.0-193.rt13.51.el8, +4 more
    fixed: vendor fix RHSA-2020:1567
  • 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
18 mo 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 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • openEuler kernel

Classification

Weakness

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.