CVE-2026-6386— Missing large page handling in pmap_pkru_update_range()
Quick assessment
Affected
FreeBSD FreeBSD
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
FreeBSD是FreeBSD基金会的一套类Unix操作系统。 FreeBSD存在安全漏洞，该漏洞源于内核子程序在更新页表条目时未考虑使用shm_create_largepage接口创建的1GB大页映射，可能导致无特权用户滥用此漏洞，使pmap_pkru_update_range将用户空间内存视为页表页并覆盖内存。
Possible ATT&CK Techniques 2 AI
T1068 · Exploitation for Privilege Escalation T1055 · Process Injection
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I. Basic Information for CVE-2026-6386
Vulnerability Information
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Vulnerability Title
Missing large page handling in pmap_pkru_update_range()
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
特权管理不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
FreeBSD 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FreeBSD是FreeBSD基金会的一套类Unix操作系统。 FreeBSD存在安全漏洞，该漏洞源于内核子程序在更新页表条目时未考虑使用shm_create_largepage接口创建的1GB大页映射，可能导致无特权用户滥用此漏洞，使pmap_pkru_update_range将用户空间内存视为页表页并覆盖内存。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-6386
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Vendor Advisories for CVE-2026-6386 (1)
IV. Related Vulnerabilities
Same product: FreeBSD
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CVE-2026-58094
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Same vendor: FreeBSD
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Kernel use-after-free via tty ioctls -
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Same weakness: CWE-269
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V. Comments for CVE-2026-6386
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