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CVE-2026-49427— posixshm: largepage shared memory objects not explicitly wired

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.

大型页面共享内存对象所属的页面未被显式固定（wired）。当 sendfile(2) 系统调用以 SF_NOCACHE 标志传输此类对象时，即使仍有现有映射引用这些页面，它也会在传输完成后释放底层页面。 未经权限的本地用户可以利用此漏洞访问已释放的内核内存，从而可能被用于提升权限（privilege escalation）。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.27% · P20

Affected Version Matrix 4

VendorProduct Version RangeStatus
FreeBSD FreeBSD 15.1-RELEASE< p1 affected
15.0-RELEASE< p11 affected
14.4-RELEASE< p7 affected
14.3-RELEASE< p16 affected
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I. Basic Information for CVE-2026-49427

Vulnerability Information
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Vulnerability Title
posixshm: largepage shared memory objects not explicitly wired
Source: CVE Program / CVE List V5
Vulnerability Description
Pages belonging to largepage shared memory objects were not explicitly wired. When sendfile(2) transmitted such an object with the SF_NOCACHE flag, it freed the underlying pages after transmission even though existing mappings still referred to them. An unprivileged local user can abuse the bug to access freed kernel memory. This can be exploited to escalate privileges.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-826
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeBSD FreeBSD 15.1-RELEASE ~ p1 -

II. Public POCs for CVE-2026-49427

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III. Intelligence Information for CVE-2026-49427

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Vendor Advisories for CVE-2026-49427 (1)

Same Patch Batch · FreeBSD · 2026-08-19 · 23 CVEs total

CVE-2026-49423 Remote DOS via uninitialized memory access in KTLS receive
CVE-2026-58087 Heap out-of-bounds access in semctl(2)
CVE-2026-58088 Race condition in ELF core dump segment counting
CVE-2026-58083 Use-after-free in kqueue copy-on-fork
CVE-2026-58084 Kernel stack disclosure via timer_settime(2)
CVE-2026-58085 Missing MAC validation in wg(4) packet decryption
CVE-2026-58086 ktrace(2) privilege incorrectly validated in jails
CVE-2026-49425 Kernel stack disclosure in 32-bit compatibility support
CVE-2026-49424 Kernel stack disclosure in Linux compatibility layer
CVE-2026-58081 Heap based buffer overflow in iconv(3)
CVE-2026-58082 Stack based buffer overflow in iconv(3)
CVE-2026-49418 Use-after-free in device pager page list
CVE-2026-49426 Incorrect audit records for ptrace(2) syscall requests
CVE-2026-49428 posixshm: system calls can incorrectly free memory of largepage objects
CVE-2026-49420 Buffer overflow in libalias RTSP handler
CVE-2026-49422 Use-after-free in TCP RACK stack option handler
CVE-2026-49421 unlinkat(2) ignores AT_RESOLVE_BENEATH flag
CVE-2026-49430 Kernel heap overflow in ZFS_IOC_RECV_NEW ioctl
CVE-2026-49429 Kernel heap overflow in ZFS_IOC_USERSPACE_MANY ioctl
CVE-2026-49431 Incorrect user validation in ZFS_IOC_SET_PROP ioctl

Showing top 20 of 23 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: FreeBSD
Same vendor: FreeBSD
Same weakness: CWE-826

V. Comments for CVE-2026-49427

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