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Fencer Vulns
medium 4.5

CVE-2020-35508 json

A flaw possibility of race condition and incorrect initialization of the process id was found in the Linux kernel child/parent process iden…

published 2021-03-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-23177

cvss
4.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

A flaw possibility of race condition and incorrect initialization of the process id was found in the Linux kernel child/parent process identification handling while filtering signal handlers. A local attacker is able to abuse this flaw to bypass checks to send any signal to a privileged process.

Patch / fix

  • linux linux_kernel 5.12
  • linux Debian 14, Debian 13, Debian 12 5.9.9-1

debian advisories DEBIAN-CVE-2020-35508

  • linux Ubuntu 16.04 LTS 4.4.0-198.230
  • linux Ubuntu 18.04 LTS 4.15.0-129.132
  • linux Ubuntu 20.04 LTS 5.4.0-59.65
  • linux-aws Ubuntu 16.04 LTS 4.4.0-1119.133
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1091.96
  • linux-aws Ubuntu 20.04 LTS 5.4.0-1034.35
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1091.104~16.04.1
  • linux-gcp Ubuntu 20.04 LTS 5.4.0-1033.35

ubuntu advisories UBUNTU-CVE-2020-35508

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 4.18.0-305.el8
  • perf RHEL 8 4.18.0-305.el8
  • bpftool RHEL 8 4.18.0-305.el8
  • kernel-core RHEL 8 4.18.0-305.el8
  • kernel-tools RHEL 8 4.18.0-305.el8
  • python3-perf RHEL 8 4.18.0-305.el8
  • kernel-modules RHEL 8 4.18.0-305.el8
  • kernel-zfcpdump RHEL 8 4.18.0-305.el8

red hat advisories RHSA-2021:1578RHSA-2021:1739RHSA-2021:2719RHSA-2021:2718

  • kernel CBL-Mariner 2.0 5.10.78.1-1

azure linux advisories AZL-6528

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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-2020-35508 updated cvss 4.5

kernel: fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent

  • Red Hat CodeReady Linux Builder (v. 8) kernel-debuginfo-common-x86_64 4.18.0-305.el8, kernel-debuginfo-common-aarch64 4.18.0-305.el8, kernel-debuginfo-common-ppc64le 4.18.0-305.el8
    fixed: vendor fix RHSA-2021:1578
  • Red Hat CodeReady Linux Builder EUS (v. 8.2) kernel-debuginfo-common-x86_64 4.18.0-193.60.2.el8_2, kernel-debuginfo-common-aarch64 4.18.0-193.60.2.el8_2, kernel-debuginfo-common-ppc64le 4.18.0-193.60.2.el8_2
    fixed: vendor fix RHSA-2021:2718
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-305.el8, kernel 4.18.0-305.el8, bpftool 4.18.0-305.el8, kernel-core 4.18.0-305.el8, kernel-tools 4.18.0-305.el8, python3-perf 4.18.0-305.el8, +15 more
    fixed: vendor fix RHSA-2021:1578
  • Red Hat Enterprise Linux BaseOS EUS (v. 8.2) perf 4.18.0-193.60.2.el8_2, kernel 4.18.0-193.60.2.el8_2, bpftool 4.18.0-193.60.2.el8_2, kernel-core 4.18.0-193.60.2.el8_2, kernel-tools 4.18.0-193.60.2.el8_2, python3-perf 4.18.0-193.60.2.el8_2, +15 more
    fixed: vendor fix RHSA-2021:2718
  • Red Hat Enterprise Linux Real Time (v. 8) kernel-rt 4.18.0-305.rt7.72.el8, kernel-rt-core 4.18.0-305.rt7.72.el8, kernel-rt-modules 4.18.0-305.rt7.72.el8, kernel-rt-debug-core 4.18.0-305.rt7.72.el8, kernel-rt-debug-modules 4.18.0-305.rt7.72.el8, kernel-rt-modules-extra 4.18.0-305.rt7.72.el8, +2 more
    fixed: vendor fix RHSA-2021:1739
  • Red Hat Enterprise Linux Real Time EUS (v. 8.2) kernel-rt 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-core 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-modules 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-debug-core 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-debug-modules 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-modules-extra 4.18.0-193.60.2.rt13.112.el8_2, +2 more
    fixed: vendor fix RHSA-2021:2719
  • Red Hat Enterprise Linux Real Time for NFV (v. 8) kernel-rt 4.18.0-305.rt7.72.el8, kernel-rt-kvm 4.18.0-305.rt7.72.el8, kernel-rt-core 4.18.0-305.rt7.72.el8, kernel-rt-modules 4.18.0-305.rt7.72.el8, kernel-rt-debug-kvm 4.18.0-305.rt7.72.el8, kernel-rt-debug-core 4.18.0-305.rt7.72.el8, +4 more
    fixed: vendor fix RHSA-2021:1739
  • Red Hat Enterprise Linux Real Time for NFV EUS (v. 8.2) kernel-rt 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-kvm 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-core 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-modules 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-debug-kvm 4.18.0-193.60.2.rt13.112.el8_2, kernel-rt-debug-core 4.18.0-193.60.2.rt13.112.el8_2, +4 more
    fixed: vendor fix RHSA-2021:2719
show 1 more
  • 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, bpftool, kernel-rt, kernel-alt, python-perf, +9 more Red Hat Enterprise MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    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

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 4.5 CVSS:3.1/AV:L/AC:H/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

Affected products

  • n/a kernel

Classification

Weakness
  • CWE-665 Improper Initialization
  • CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization
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.