Skip to content
Fencer Vulns
high 7.8

CVE-2020-36791 json

net_sched: keep alloc_hash updated after hash allocation

published 2025-05-07 18 mo ago modified 2026-08-05 3 mo ago also EUVD-2020-24232

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 9%
public exploits
0
none known

Summary

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

net_sched: keep alloc_hash updated after hash allocation

In commit 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex") I moved cp->hash calculation before the first tcindex_alloc_perfect_hash(), but cp->alloc_hash is left untouched. This difference could lead to another out of bound access.

cp->alloc_hash should always be the size allocated, we should update it after this tcindex_alloc_perfect_hash().

Patch / fix

  • Linux Linux 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-2020-36791

  • 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-2020-36791

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 SLE Micro 5.2, SLE Micro 5.1 5.3.18-150300.211.1
  • kernel-source-rt SLE Micro 5.2, SLE Micro 5.1 5.3.18-150300.211.1
  • kernel-64kb SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS, Enterprise Storage 7.1 5.3.18-150300.59.207.1
  • kernel-syms SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.207.1
  • kernel-source SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.207.1
  • kernel-default SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE Micro 5.2 +5 more 5.3.18-150300.59.207.1
  • kernel-preempt SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.207.1
  • kernel-obs-build SLES for SAP 15 SP3, SLES 15 SP3-LTSS, SLE High Performance Computing 15 SP3-LTSS +1 more 5.3.18-150300.59.207.1

suse advisories SUSE-SU-2025:01995-1SUSE-SU-2025:01983-1SUSE-SU-2025:01982-1

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-2020-36791 updated cvss 5.5

kernel: net_sched: keep alloc_hash updated after hash allocation

  • 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
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    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

0.20% chance of exploitation in the next 30 days, higher than 9% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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.