CVE-2026-6386 (Medium) detected in multiple libraries

[mend-bolt-for-github]

CVE-2026-6386 - Medium Severity Vulnerability

Vulnerable Libraries - freebsd-srcrelease/13.5.0-p11, freebsd-srcrelease/13.5.0-p11, src4.0.4, src4.0.4

freebsd-srcrelease/13.5.0-p11

The FreeBSD src tree publish-only repository. Experimenting with 'simple' pull requests....

Library home page: https://github.com/freebsd/freebsd-src.git

Vulnerable Source Files (1)

freebsd-srcrelease/13.5.0-p11

The FreeBSD src tree publish-only repository. Experimenting with 'simple' pull requests....

Library home page: https://github.com/freebsd/freebsd-src.git

Vulnerable Source Files (1)

src4.0.4

Library home page: https://github.com/MidnightBSD/src.git

Vulnerable Source Files (1)

src4.0.4

Library home page: https://github.com/MidnightBSD/src.git

Vulnerable Source Files (1)

Found in base branch: stable/4.0

Vulnerability Details

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.

Publish Date: 2026-04-22

URL: CVE-2026-6386

CVSS 3 Score Details (6.2)

Base Score Metrics:

• Exploitability Metrics:
  • Attack Vector: Local
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: None
  • Scope: Unchanged
• Impact Metrics:
  • Confidentiality Impact: High
  • Integrity Impact: None
  • Availability Impact: None

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Release Date: 2026-04-22

Fix Resolution: https://github.com/freebsd/freebsd-src.git - release/14.3.0-p11,https://github.com/freebsd/freebsd-src.git - release/15.0.0-p6,https://github.com/freebsd/freebsd-src.git - release/14.4.0-p2,https://github.com/freebsd/freebsd-src.git - release/13.5.0-p12

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