CVE intelligence and bounded remediation

CVE-2026-6386 — In order to apply a particular protection key to an address range, the kernel must update the corresponding page table entries

Medium CVSS 6.2

In 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.

Severity
Medium
CVSS
6.2 (3.1)
Published
2026-04-22
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-269, CWE-732

Affected products

  • freebsd / freebsd / 13.5

Showing 1 representative product identities from 33 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Privilege escalation and unsafe privilege management

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Check exposure

  • Map service accounts, operating-system identities, roles, capabilities, impersonation, set-user transitions, and administrative helper paths.
  • Determine whether untrusted users or lower-privilege processes can reach the affected transition or modify inputs it trusts.
  • Review file, socket, registry, device, job, container, and cloud-role permissions used before and after privilege changes.

Remediate safely

  • Apply the supported fix and redesign privileged operations as a minimal, authenticated, allowlisted interface.
  • Drop privileges before processing untrusted input, verify the drop succeeds, and remove unnecessary roles, capabilities, and write permissions.
  • Validate ownership and permissions at time of use and add explicit lower-to-higher privilege boundary tests.

Authoritative sources

Complete CVE record and remediation plan

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