CVE-2026-6386

Protected-memory overwrite via misclassified large-page entry

Published Apr 22, 2026 · Updated Apr 22, 2026

Memory corruption in the FreeBSD amd64 kernel allows local users to overwrite protected process memory through 1GB large-page mappings. The pmap_pkru_update_range() routine assumes every page-directory entry points to another page-table page and fails to recognize 1GB mappings created by shm_create_largepage(3). Exploitation requires an unprivileged local account on an amd64 system and permits writes to memory otherwise inaccessible to the calling application.

CVSS severity6.2
Medium
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in the FreeBSD amd64 kernel allows local users to overwrite protected process memory through 1GB large-page mappings. The pmap_pkru_update_range() routine assumes every page-directory entry points to another page-table page and fails to recognize 1GB mappings created by shm_create_largepage(3). Exploitation requires an unprivileged local account on an amd64 system and permits writes to memory otherwise inaccessible to the calling application.

The record

CVE
CVE-2026-6386
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The FreeBSD Project
Product
FreeBSD
Classifications
CWE-269, CWE-732
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2026Record 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=13.5-RELEASE <p12
  2. Affected versionversion=14.3-RELEASE <p11
  3. Affected versionversion=14.4-RELEASE <p2
  4. Affected versionversion=15.0-RELEASE <p6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The FreeBSD Project · FreeBSDversion=13.5-RELEASE <p12; version=14.3-RELEASE <p11; version=14.4-RELEASE <p2; version=15.0-RELEASE <p6

Published CVSS scores

6.2CISA-ADPCVSS:3.1/AV:L/AC:L/PR:N/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.

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)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-269Improper Privilege Management
CWE-732Incorrect Permission Assignment for Critical Resource

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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