CVE-2021-29628Network attack vector

Kernel integrity bypass via SMAP disablement

Published May 28, 2021 · Updated Aug 3, 2024

Privilege escalation in FreeBSD 13.0-RELEASE before p1 and 12.2-RELEASE before p7 allows attackers to bypass SMAP via a faulting system call. The amd64 kernel fault path can leave Supervisor Mode Access Prevention disabled for the remainder of that system call after handling a fault. Exploitation requires reaching a system-call fault and combining the protection bypass with another kernel weakness; the stated consequence is loss of kernel memory integrity protections.

CVSS severity7.5
High
EPSS probability1.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Privilege escalation in FreeBSD 13.0-RELEASE before p1 and 12.2-RELEASE before p7 allows attackers to bypass SMAP via a faulting system call. The amd64 kernel fault path can leave Supervisor Mode Access Prevention disabled for the remainder of that system call after handling a fault. Exploitation requires reaching a system-call fault and combining the protection bypass with another kernel weakness; the stated consequence is loss of kernel memory integrity protections.

The record

CVE
CVE-2021-29628
Published
May 28, 2021
Updated
Aug 3, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-863, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 28, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=FreeBSD 13.0-RELEASE before p1, 12.2-RELEASE before p7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 13.0-RELEASE before p1, 12.2-RELEASE before p7

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo