CVE-2021-33624

MEDIUM

Linux kernel <5.12.13 - Memory Corruption

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 2 public exploits for CVE-2021-33624. PoCs published by benschlueter.

AI-analyzed exploit summary This repository contains a functional proof-of-concept exploit for CVE-2021-33624, a type confusion vulnerability in the Linux kernel's BPF verifier. The exploit leverages speculative execution to leak kernel memory by mis-training the branch predictor using DIV instructions.

Description

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.

Exploits (2)

nomisec WORKING POC 3 stars
by benschlueter · poc
https://github.com/benschlueter/CVE-2021-33624

This repository contains a functional proof-of-concept exploit for CVE-2021-33624, a type confusion vulnerability in the Linux kernel's BPF verifier. The exploit leverages speculative execution to leak kernel memory by mis-training the branch predictor using DIV instructions.

Classification
Working Poc 95%
Attack Type
Info Leak
Complexity
Complex
Reliability
Racy
Target: Linux kernel (specific versions affected by CVE-2021-33624)
Auth required
Prerequisites: Root access (sudo privileges) · Specific CPU architecture with vulnerable branch predictor · Kernel with BPF support
devstral-2 · analyzed Feb 18, 2026 Full analysis →
inthewild WORKING POC
poc
https://github.com/kakashiiiiy/cve-2021-33624

This repository contains a functional proof-of-concept exploit for CVE-2021-33624, a type confusion vulnerability in the Linux kernel's BPF (Berkeley Packet Filter) subsystem. The exploit leverages speculative execution to leak kernel memory by mis-training the branch predictor using DIV instructions.

Classification
Working Poc 95%
Attack Type
Info Leak
Complexity
Complex
Reliability
Racy
Target: Linux kernel (BPF subsystem)
Auth required
Prerequisites: Linux kernel with BPF support · sudo privileges · specific CPU architecture with speculative execution
devstral-2 · analyzed Feb 23, 2026 Full analysis →

Scores

CVSS v3 4.7
EPSS 0.0047
EPSS Percentile 65.3%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Details

CWE
CWE-843
Status published
Products (2)
debian/debian_linux 9.0
linux/linux_kernel < 5.12.13
Published Jun 23, 2021
Tracked Since Feb 18, 2026