CVE-2025-21963: linux kernel Integer Overflow — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: Fix integer overflow while processing acdirmax mount option User-provided mount parameter acdirmax of type u32 is intended to have an upper limit, but before it is validated, the value is converted from seconds to jiffies which can lead to an integer overflow. Found by Linux Verification Center (linuxtesting.org) with SVACE.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-190 Integer Overflow

Affected Products

Vendor	Product	Versions
linux	linux_kernel	5.12 — 5.15.180
linux	linux_kernel	5.16 — 6.1.132
linux	linux_kernel	6.2 — 6.6.84
linux	linux_kernel	6.7 — 6.12.20
linux	linux_kernel	6.13 — 6.13.8
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0c26edf477e093cefc41637f5bccc102e1a77399 https://git.kernel.org/stable/c/2809a79bc64964ce02e0c5f2d6bd39b9d09bdb3c https://git.kernel.org/stable/c/39d086bb3558da9640ef335f97453e01d32578a1 https://git.kernel.org/stable/c/5b29891f91dfb8758baf1e2217bef4b16b2b165b https://git.kernel.org/stable/c/6124cbf73e3dea7591857dd63b8ccece28952afd https://git.kernel.org/stable/c/9e438d0410a4002d24f420f2c28897ba2dc0af64

Other References

https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

Frequently Asked Questions

What is CVE-2025-21963? +

In the Linux kernel, the following vulnerability has been resolved: cifs: Fix integer overflow while processing acdirmax mount option User-provided mount parameter acdirmax of type u32 is intended to have an upper limit, but before it is validated, the value is converted from seconds to jiffies which can lead to an integer overflow. Found by Linux Verification Center (linuxtesting.org) with SVACE. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21963? +

CVE-2025-21963 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21963? +

CVE-2025-21963 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21963? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-21963