CVE-2021-29626

Private-memory disclosure via stale page mappings

Published Apr 7, 2021 · Updated Aug 3, 2024

Use-after-free in FreeBSD before 13.0-RC5-p1, 12.2-RELEASE-p6, or 11.4-RELEASE-p9 allows local users to read private memory. The VM copy-on-write path fails to invalidate sibling mappings of a source page after a descendant process writes, leaving mappings valid after page reuse. An unprivileged local user can construct the ancestor-descendant sharing relationship and read data later assigned to another process or the kernel.

CVSS severity5.5
Medium
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in FreeBSD before 13.0-RC5-p1, 12.2-RELEASE-p6, or 11.4-RELEASE-p9 allows local users to read private memory. The VM copy-on-write path fails to invalidate sibling mappings of a source page after a descendant process writes, leaving mappings valid after page reuse. An unprivileged local user can construct the ancestor-descendant sharing relationship and read data later assigned to another process or the kernel.

The record

CVE
CVE-2021-29626
Published
Apr 7, 2021
Updated
Aug 3, 2024
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-416, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 7, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=FreeBSD 12.2-RELEASE before p6, 11.4-RELEASE before p9

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=FreeBSD 12.2-RELEASE before p6, 11.4-RELEASE before p9

Published CVSS scores

2.1NIST NVDAV:L/AC:L/Au:N/C:P/I:N/A:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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