CVE-2026-6386
Missing large page handling in pmap_pkru_update_range()
Description
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.
INFO
Published Date :
April 22, 2026, 3:16 a.m.
Last Modified :
May 1, 2026, 12:49 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Apply kernel updates for pmap_pkru_update_range.
- Avoid using shm_create_largepage(3) if possible.
- Test kernel memory management functions thoroughly.
Public PoC/Exploit Available at Github
CVE-2026-6386 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-6386.
| URL | Resource |
|---|---|
| https://security.freebsd.org/advisories/FreeBSD-SA-26:11.amd64.asc | Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-6386 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-6386
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Tracking Vulnerabilities That Appear to be Credited to the Anthropic Research Team
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-6386 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-6386 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
May. 01, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:o:freebsd:freebsd:15.0:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p8:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p9:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p2:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p5:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p6:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p7:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p8:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:rc1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p9:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:-:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p4:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:beta3:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p10:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:13.5:p11:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.3:p10:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:14.4:p1:*:*:*:*:*:* *cpe:2.3:o:freebsd:freebsd:15.0:p5:*:*:*:*:*:* Added Reference Type FreeBSD: https://security.freebsd.org/advisories/FreeBSD-SA-26:11.amd64.asc Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Apr. 22, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N -
New CVE Received by [email protected]
Apr. 22, 2026
Action Type Old Value New Value Added Description 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. Added CWE CWE-269 Added CWE CWE-732 Added Reference https://security.freebsd.org/advisories/FreeBSD-SA-26:11.amd64.asc