Missing large page handling in pmap_pkru_update_range()

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Summary

CVECVE-2026-6386
StatePUBLISHED
Assignerfreebsd
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-22 03:16:01 UTC
Updated2026-04-22 21:23:52 UTC
DescriptionIn order to apply a particular protection key to an address range, the kernel must update the corresponding page table entries. The subroutine which handled this failed to take into account the presence of 1GB largepage mappings created using the shm_create_largepage(3) interface. In particular, it would always treat a page directory page entry as pointing to another page table page. The bug can be abused by an unprivileged user to cause pmap_pkru_update_range() to treat userspace memory as a page table page, and thus overwrite memory to which the application would otherwise not have access.

Risk And Classification

Primary CVSS: v3.1 6.2 MEDIUM from ADP

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.000170000 probability, percentile 0.042100000 (date 2026-04-22)

Problem Types: CWE-269 | CWE-732 | CWE-269 CWE-269 Improper Privilege Management | CWE-732 CWE-732 Incorrect Permission Assignment for Critical Resource

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED6.2MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary6.2MEDIUMCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA FreeBSD FreeBSD affected 15.0-RELEASE p6 release Not specified
CNA FreeBSD FreeBSD affected 14.4-RELEASE p2 release Not specified
CNA FreeBSD FreeBSD affected 14.3-RELEASE p11 release Not specified
CNA FreeBSD FreeBSD affected 13.5-RELEASE p12 release Not specified

References

ReferenceSourceLinkTags
security.freebsd.org/advisories/FreeBSD-SA-26:11.amd64.asc [email protected] security.freebsd.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Nicholas Carlini using Claude, Anthropic (en)

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