CVE-2021-29627

HIGH

FreeBSD 12.0-12.2 - Double Free in Accept Filter accf_create Callback

Title source: llm
STIX 2.1

Exploitation Summary

EIP tracks 1 public exploit for CVE-2021-29627. PoCs published by raymontag.

AI-analyzed exploit summary This repository contains a functional exploit PoC for CVE-2021-29627, targeting a FreeBSD kernel vulnerability in the accept filter mechanism. The exploit includes a kernel module and user-space code to trigger the bug via mac_set_fd spray and socket manipulation.

Description

In FreeBSD 13.0-STABLE before n245050, 12.2-STABLE before r369525, 13.0-RC4 before p0, and 12.2-RELEASE before p6, listening socket accept filters implementing the accf_create callback incorrectly freed a process supplied argument string. Additional operations on the socket can lead to a double free or use after free.

Exploits (1)

nomisec WORKING POC 13 stars
by raymontag · poc
https://github.com/raymontag/cve-2021-29627

This repository contains a functional exploit PoC for CVE-2021-29627, targeting a FreeBSD kernel vulnerability in the accept filter mechanism. The exploit includes a kernel module and user-space code to trigger the bug via mac_set_fd spray and socket manipulation.

Classification
Working Poc 90%
Attack Type
Lpe
Complexity
Moderate
Reliability
Theoretical
Target: FreeBSD kernel (accept filter mechanism)
No auth needed
Prerequisites: FreeBSD system with vulnerable kernel · Ability to load kernel modules
devstral-2 · analyzed Feb 18, 2026 Full analysis →

References (2)

Core 2
Core References
Third Party Advisory x_refsource_confirm
https://security.netapp.com/advisory/ntap-20210423-0007/

Scores

CVSS v3 7.8
EPSS 0.0075
EPSS Percentile 50.3%
Attack Vector LOCAL
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Details

CWE
CWE-415 CWE-416
Status published
Products (3)
freebsd/freebsd 12.2 (3 CPE variants)
freebsd/freebsd 13.0 beta1 (7 CPE variants)
freebsd/freebsd 12.0 - 12.2
Published Apr 07, 2021
Tracked Since Feb 18, 2026