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CVE-2026-58087— Heap out-of-bounds access in semctl(2)

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.

semctl(2) 中的 GETALL 和 SETALL 命令存在以下流程缺陷：首先记录目标信号量集中的信号量数量，随后释放保护该集合的锁，接着基于该数量分配缓冲区，最后重新获取锁。系统使用序列号来验证在此期间集合未被替换，但该序列号在经历 0x8000 次创建/销毁周期后会回绕。 攻击者可通过在同一索引处快速销毁并重新创建信号量集，使序列号回绕，从而使得包含不同数量信号量的集合通过验证。随后进行的拷贝操作将在已分配缓冲区末尾之外读取或写入数据。 未提权的本地用户可触发内核堆内存越界读取和写入，可能导致提权。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 3

VendorProduct Version RangeStatus
FreeBSD FreeBSD 15.1-RELEASE< p2 affected
15.0-RELEASE< p12 affected
14.4-RELEASE< p8 affected
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I. Basic Information for CVE-2026-58087

Vulnerability Information
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Vulnerability Title
Heap out-of-bounds access in semctl(2)
Source: CVE Program / CVE List V5
Vulnerability Description
The GETALL and SETALL commands in semctl(2) recorded the number of semaphores in the target set, dropped the lock protecting the set, allocated a buffer sized for that count, and reacquired the lock. A sequence-number check was used to verify that the set had not been replaced in the interim, but the sequence number wraps after 0x8000 create/destroy cycles. By rapidly destroying and recreating semaphore sets at the same index, another process can cause the sequence number to wrap, allowing a set with a different number of semaphores to pass validation. The subsequent copy then reads or writes past the end of the allocated buffer. An unprivileged local user can trigger out-of-bounds reads and writes on kernel heap memory, potentially leading to privilege escalation.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeBSD FreeBSD 15.1-RELEASE ~ p2 -

II. Public POCs for CVE-2026-58087

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III. Intelligence Information for CVE-2026-58087

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Vendor Advisories for CVE-2026-58087 (1)

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

CVE-2026-49426 Incorrect audit records for ptrace(2) syscall requests
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-2026-49423 Remote DOS via uninitialized memory access in KTLS receive
CVE-2026-49418 Use-after-free in device pager page list
CVE-2026-49427 posixshm: largepage shared memory objects not explicitly wired
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-191

V. Comments for CVE-2026-58087

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