CVE-2021-20239

Severity: low (CVSS 3.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-28 · updated 2026-06-17
Weakness: CWE-822

Description

A flaw was found in the Linux kernel in versions before 5.4.92 in the BPF protocol. This flaw allows an attacker with a local account to leak information about kernel internal addresses. The highest threat from this vulnerability is to confidentiality.

Affected products

Fedoraproject Fedora: 33
Linux kernel: before 5.4.92 — fixed in 5.4.92
Red Hat Enterprise Linux: 5.0, 6.0, 8.0

How to fix

Upgrade to a fixed version: Linux kernel 5.4.92. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1923636
https://bugzilla.redhat.com/show_bug.cgi?id=1923636

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