TI-2021-12999 Aliases CVE-2021-33624 GHSA-w9w3-f8q7-x576

In kernel/bpf/verifier.c in the Linux kernel before 5.12.13, a branch can be mispredicted…

LOW 23CWE-843Published 2021-06-23 · Updated 2026-10-08

Key facts

Attack vector: Local
Privileges required: Low
User interaction: None
Attack complexity: High
Impact type: —
Confidentiality · integrity · availability: High · None · None
Fix status: No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.0093 60th percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
—	—	all versions	—	No fix listed	CNA

— Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPE	Versions	Role	Vendor
cpe:2.3:o:linux:linux_kernel::::::::	before 5.12.13	Vulnerable	Linux
cpe:2.3:o:debian:debian_linux:9.0:::::::*	9.0	Vulnerable	Debian

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions before 5.12.13 Vulnerable ·Linux
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* Versions 9.0 Vulnerable ·Debian

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
Red Hat Enterprise Linux 7	Affected	No fix planned: Will not fix
Red Hat Enterprise Linux 8	Affected	No fix yet

Not affected: 2 products

Red Hat Enterprise Linux 6
Red Hat Enterprise Linux 9

Timeline

2026-10-02 Threatist record created from CVE-2021-33624
2026-10-03 Alias added: GHSA-w9w3-f8q7-x576
2026-10-08 CISA SSVC decision points changed

References

Exploit 1

http://www.openwall.com/lists/oss-security/2021/06/21/1

Patch 1

https://github.com/torvalds/linux/commit/9183671af6dbf60a1219371d4ed73e23f43b49db

Advisory 2

Other 1

https://github.com/benschlueter/CVE-2021-33624

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences