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Fencer Intel
medium 5.3

CVE-2020-12826 json

A signal access-control issue was discovered in the Linux kernel before 5.6.5, aka CID-7395ea4e65c2.

published 6y ago modified 4mo ago also EUVD-2020-5109

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.7%
EPSS 0.7% chance of exploitation in 30 days, percentile 53%
public exploits
0
none known

Summary

A signal access-control issue was discovered in the Linux kernel before 5.6.5, aka CID-7395ea4e65c2. Because exec_id in include/linux/sched.h is only 32 bits, an integer overflow can interfere with a do_notify_parent protection mechanism. A child process can send an arbitrary signal to a parent process in a different security domain. Exploitation limitations include the amount of elapsed time before an integer overflow occurs, and the lack of scenarios where signals to a parent process present a substantial operational threat.

Patch / fix

  • linux linux_kernel 5.6.5
  • linux Debian 14, Debian 13, Debian 12 5.6.7-1

debian advisories DEBIAN-CVE-2020-12826

  • linux Ubuntu 16.04 LTS 4.4.0-184.214
  • linux Ubuntu 18.04 LTS 4.15.0-101.102
  • linux Ubuntu 20.04 LTS 5.4.0-31.35
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1109.120
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1067.71
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1011.11
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1071.81~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1011.11

ubuntu advisories UBUNTU-CVE-2020-12826

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-2020:4431RHSA-2020:4060RHSA-2020:4609RHSA-2020:4062

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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-2020-12826 updated cvss 5.3

kernel: possible to send arbitrary signals to a privileged (suidroot) parent process

  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, kernel-alt, python-perf, kernel-kdump, kernel-tools, +3 more
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Enterprise MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    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 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 Client (v. 7) perf 3.10.0-1160.el7, kernel 3.10.0-1160.el7, bpftool 3.10.0-1160.el7, python-perf 3.10.0-1160.el7, kernel-tools 3.10.0-1160.el7, kernel-tools-libs 3.10.0-1160.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.el7 Red Hat Enterprise Linux ComputeNode (v. 7) perf 3.10.0-1160.el7, kernel 3.10.0-1160.el7, bpftool 3.10.0-1160.el7, python-perf 3.10.0-1160.el7, kernel-tools 3.10.0-1160.el7, kernel-tools-libs 3.10.0-1160.el7, +2 more Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.el7
    fixed: vendor fix RHSA-2020:4060
  • Red Hat Enterprise Linux for Real Time (v. 7) kernel-rt 3.10.0-1160.rt56.1131.el7, kernel-rt-trace 3.10.0-1160.rt56.1131.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.rt56.1131.el7 Red Hat Enterprise Linux for Real Time for NFV (v. 7) kernel-rt 3.10.0-1160.rt56.1131.el7, kernel-rt-kvm 3.10.0-1160.rt56.1131.el7, kernel-rt-trace 3.10.0-1160.rt56.1131.el7, kernel-rt-debug-kvm 3.10.0-1160.rt56.1131.el7, kernel-rt-trace-kvm 3.10.0-1160.rt56.1131.el7, kernel-rt-debuginfo-common-x86_64 3.10.0-1160.rt56.1131.el7
    fixed: vendor fix RHSA-2020:4062
  • 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 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 Server (v. 7) perf 3.10.0-1160.el7, kernel 3.10.0-1160.el7, bpftool 3.10.0-1160.el7, python-perf 3.10.0-1160.el7, kernel-kdump 3.10.0-1160.el7, kernel-tools 3.10.0-1160.el7, +7 more Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-1160.el7, kernel-debuginfo-common-x86_64 3.10.0-1160.el7, kernel-debuginfo-common-ppc64le 3.10.0-1160.el7 Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-1160.el7, kernel 3.10.0-1160.el7, bpftool 3.10.0-1160.el7, python-perf 3.10.0-1160.el7, kernel-tools 3.10.0-1160.el7, kernel-tools-libs 3.10.0-1160.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-1160.el7
    fixed: vendor fix RHSA-2020:4060

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

0.71% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-14).

Exploits and checks

  • openwall.com https://www.openwall.com/lists/kernel-hardening/2020/03/25/1 referenced PoC, tagged "exploit" by a source, unverified
  • lists.openwall.net https://lists.openwall.net/linux-kernel/2020/03/24/1803 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.3 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
NVD 2.0 4.4 AV:L/AC:M/Au:N/C:P/I:P/A:P

Classification

Weakness
  • CWE-190 Integer Overflow or Wraparound
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.