CVE-2020-36691

System crash via unbounded Netlink policy recursion

Published Mar 24, 2023 · Updated Feb 21, 2025

Uncontrolled recursion in Linux kernel before 5.8 allows local users to crash the system through nested Netlink policy validation. In lib/nlattr.c, __nla_validate_parse recursively follows nested-policy back references without tracking or limiting recursion depth. A local low-privileged user must submit suitably nested Netlink attributes, exhausting the kernel stack and interrupting the host.

CVSS severity5.5
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in Linux kernel before 5.8 allows local users to crash the system through nested Netlink policy validation. In lib/nlattr.c, __nla_validate_parse recursively follows nested-policy back references without tracking or limiting recursion depth. A local low-privileged user must submit suitably nested Netlink attributes, exhausting the kernel stack and interrupting the host.

The record

CVE
CVE-2020-36691
Published
Mar 24, 2023
Updated
Feb 21, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-674, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.5CISA-ADPCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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