CVE-2021-33624: Medium severity linux kernel vulnerability

Published Jun 23, 2021
·
Updated

In kernel/bpf/verifier.c in the Linux kernel before 5.12.13, a branch can be mispredicted (e.g., because of type confusion) and consequently an unprivileged BPF program can read arbitrary memory locations via a side-channel attack, aka CID-9183671af6db.

Affected Software

3 affected componentsFixes available
Linux Linux kernel<5.12.13
Debian Debian Linux=9.0
debian/linux
5.10.223-15.10.234-16.1.129-16.1.135-16.12.25-16.12.27-1

Event History

Jun 23, 2021
CVE Published
via MITRE·03:37 PM
Data Sourced
via MITRE·03:37 PM
Description
Data Sourced
via NVD·04:15 PM
RemedyDescriptionSeverityWeaknessAffected Software
Jan 11, 2024
Data Sourced
via Launchpad·11:57 PM
Description
Apr 28, 2025
Data Sourced
via Ubuntu·04:30 AM
RemedyDescriptionSeverityAffected Software
Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is the severity of CVE-2021-33624?

CVE-2021-33624 is classified as a medium severity vulnerability due to its potential to allow unprivileged BPF programs to read arbitrary memory locations.

2

How do I fix CVE-2021-33624?

To resolve CVE-2021-33624, update your Linux kernel to version 5.12.13 or later.

3

What type of attack does CVE-2021-33624 involve?

CVE-2021-33624 involves a side-channel attack enabled by branch misprediction due to type confusion in the BPF verifier.

4

Which versions of the Linux kernel are affected by CVE-2021-33624?

CVE-2021-33624 affects Linux kernel versions prior to 5.12.13.

5

Are there specific distributions impacted by CVE-2021-33624?

Yes, Debian and its variants are among the affected distributions for CVE-2021-33624.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203