FreeBSD Kernel pmap_pkru_update_range privileges management

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.6$0-$5k0.00

Summaryinfo

A vulnerability described as critical has been identified in FreeBSD. This affects the function pmap_pkru_update_range of the component Kernel. Executing a manipulation can lead to privileges management. This vulnerability is tracked as CVE-2026-6386. No exploit exists. A patch should be applied to remediate this issue.

Detailsinfo

A vulnerability has been found in FreeBSD (unknown version) and classified as critical. This vulnerability affects the function pmap_pkru_update_range of the component Kernel. The manipulation with an unknown input leads to a privileges management vulnerability. The CWE definition for the vulnerability is CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was disclosed by Nicholas Carlini. The advisory is available at security.freebsd.org. This vulnerability was named CVE-2026-6386 since 04/15/2026. The exploitation appears to be easy. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 04/22/2026). This vulnerability is assigned to T1068 by the MITRE ATT&CK project.

Applying a patch is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-24592). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Privileges management
CWE: CWE-269 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfo

04/15/2026 CVE reserved
04/22/2026 +7 days Advisory disclosed
04/22/2026 +0 days VulDB entry created
04/22/2026 +0 days VulDB entry last update

Sourcesinfo

Product: freebsd.org

Advisory: security.freebsd.org
Researcher: Nicholas Carlini
Status: Confirmed

CVE: CVE-2026-6386 (🔒)
GCVE (CVE): GCVE-0-2026-6386
GCVE (VulDB): GCVE-100-358762
EUVD: 🔒

Entryinfo

Created: 04/22/2026 07:34
Updated: 04/22/2026 07:53
Changes: 04/22/2026 07:34 (55), 04/22/2026 07:53 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

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