CVE-2026-45250
Received Received - Intake
Stack Buffer Overflow in FreeBSD Kernel via Supplementary Groups

Publication date: 2026-05-21

Last updated on: 2026-05-21

Assigner: FreeBSD

Description
The setcred(2) system call is only available to privileged users. However, before the privilege level of the caller is checked, the user-supplied list of supplementary groups is copied into a fixed-size kernel stack buffer without first validating its length. If the supplied list exceeds the capacity of that buffer, a stack buffer overflow occurs. Because the bounds check on the supplementary groups list occurs after the kernel stack buffer has already been written, an unprivileged local user may trigger the overflow without holding any special privilege. Successful exploitation may allow an attacker to execute arbitrary code in the context of the kernel, allowing an unprivileged local user to gain elevated privileges on the affected system.
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Meta Information
Published
2026-05-21
Last Modified
2026-05-21
Generated
2026-05-21
AI Q&A
2026-05-21
EPSS Evaluated
N/A
NVD
CVE-2026-45250
EUVD
EUVD-2026-31252
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
freebsd freebsd From 2026-01-06 (inc) to 2026-05-20 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-121 A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

CVE-2026-45250 is a stack buffer overflow vulnerability in FreeBSD's setcred(2) system call. The vulnerability arises because the system call copies a user-supplied list of supplementary groups into a fixed-size kernel stack buffer without first validating the length of that list.

Since the bounds check on the supplementary groups list occurs only after the buffer has been written, an unprivileged local user can trigger a stack buffer overflow by providing a list that exceeds the buffer's capacity.

This flaw allows an attacker to execute arbitrary code in the kernel context, potentially leading to privilege escalation.


How can this vulnerability impact me? :

This vulnerability can allow an unprivileged local user to execute arbitrary code within the kernel, which can lead to gaining elevated privileges on the affected FreeBSD system.

Successful exploitation means an attacker could take full control of the system, bypassing normal security restrictions.


What immediate steps should I take to mitigate this vulnerability?

To mitigate the CVE-2026-45250 vulnerability, users should upgrade their FreeBSD systems by applying the official patches released by the FreeBSD Project for stable and release branches.

  • Use pkg or freebsd-update tools to install the patches.
  • Alternatively, apply the source code patches provided by the FreeBSD Project.
  • After patching, perform a system reboot to ensure the updates take effect.

No workaround is available, so timely patching and rebooting are critical.


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