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CVE-2026-45251— Kernel use-after-free via file descriptor syscalls

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存在资源管理错误漏洞，该漏洞源于文件描述符关闭时线程阻塞在poll或select调用中，内核在释放对象前未能从对象等待队列中移除阻塞线程，导致释放后重用，可能被无特权本地用户触发并利用获取超级用户权限。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.17% · P7

Affected Version Matrix 3

VendorProduct Version RangeStatus
FreeBSD FreeBSD 15.0-RELEASE< p9 affected
14.4-RELEASE< p5 affected
14.3-RELEASE< p14 affected
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I. Basic Information for CVE-2026-45251

Vulnerability Information
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Vulnerability Title
Kernel use-after-free via file descriptor syscalls
Source: CVE Program / CVE List V5
Vulnerability Description
A file descriptor can be closed while a thread is blocked in a poll(2) or select(2) call waiting for that descriptor. Because the blocked thread does not hold a reference to the underlying object, this closure may result in the object being freed while the thread remains blocked. In this situation, the kernel must remove the blocked thread from the per-object wait queue prior to freeing the object. In the case of some file descriptor types, the kernel failed to unlink blocked threads from the object before freeing it. When the blocked thread is subsequently woken, it accesses memory that has already been freed resulting in a use-after-free vulnerability. The use-after-free vulnerability may be triggered by an unprivileged local user and can be exploited to obtain superuser privileges.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
释放后使用
Source: CVE Program / CVE List V5
Vulnerability Title
FreeBSD 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
FreeBSD是FreeBSD基金会的一套类Unix操作系统。 FreeBSD存在资源管理错误漏洞，该漏洞源于文件描述符关闭时线程阻塞在poll或select调用中，内核在释放对象前未能从对象等待队列中移除阻塞线程，导致释放后重用，可能被无特权本地用户触发并利用获取超级用户权限。
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

Vendor Product Affected Versions CPE Subscribe
FreeBSD FreeBSD 15.0-RELEASE ~ p9 -

II. Public POCs for CVE-2026-45251

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III. Intelligence Information for CVE-2026-45251

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Vendor Advisories for CVE-2026-45251 (1)

Same Patch Batch · FreeBSD · 2026-05-21 · 7 CVEs total

CVE-2026-45250 Stack buffer overflow via setcred(2)
CVE-2026-45252 Heap overflow in FUSE_LISTXATTR
CVE-2026-45255 Remote code execution via installer Wi-Fi access point scans
CVE-2026-45253 Missing validation in ptrace(PT_SC_REMOTE)
CVE-2026-45254 Incorrect libcap_net limitation list manipulation
CVE-2026-39461 select(2) file descriptor set overflow causes stack overflow

IV. Related Vulnerabilities

Same product: FreeBSD
Same vendor: FreeBSD
Same weakness: CWE-416

V. Comments for CVE-2026-45251

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