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CVE-2026-58084— Kernel stack disclosure via timer_settime(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.

为了获取之前的定时器值，内核会调用 realtimer_gettime()，该函数用于获取定时器时钟的当前时间。对于使用 CLOCK_TAI 的定时器，如果尚未配置 TAI 偏移量，则此操作可能会失败。然而，代码未检查该函数的错误返回值，导致将未初始化的输出缓冲区复制到用户空间。 具有本地非特权访问权限的用户可以通过创建一个使用 CLOCK_TAI 的 POSIX 定时器并调用 timer_settime(2)，从而获取未初始化的内核栈内存，这可能导致敏感内核数据泄露。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.18% · P8

Affected Version Matrix 2

VendorProduct Version RangeStatus
FreeBSD FreeBSD 15.1-RELEASE< p2 affected
15.0-RELEASE< p12 affected
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I. Basic Information for CVE-2026-58084

Vulnerability Information
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Vulnerability Title
Kernel stack disclosure via timer_settime(2)
Source: CVE Program / CVE List V5
Vulnerability Description
To retrieve the previous timer value, the kernel calls realtimer_gettime(), which obtains the current time for the timer's clock. For a timer using CLOCK_TAI this can fail when no TAI offset has been configured, but the error return was not checked, so the uninitialized output buffer was copied to userspace. An unprivileged local user can obtain uninitialized kernel stack memory by creating a POSIX timer with CLOCK_TAI and calling timer_settime(2), potentially disclosing sensitive kernel data.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
对未经初始化资源的使用
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-2026-58084

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III. Intelligence Information for CVE-2026-58084

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Vendor Advisories for CVE-2026-58084 (1)

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

CVE-2026-49426 Incorrect audit records for ptrace(2) syscall requests
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-2026-58085 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-908

V. Comments for CVE-2026-58084

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