CVE-2025-21736: linux kernel Integer Overflow — Fix

Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix possible int overflows in nilfs_fiemap() Since nilfs_bmap_lookup_contig() in nilfs_fiemap() calculates its result by being prepared to go through potentially maxblocks == INT_MAX blocks, the value in n may experience an overflow caused by left shift of blkbits. While it is extremely unlikely to occur, play it safe and cast right hand expression to wider type to mitigate the issue. Found by Linux Verification Center (linuxtesting.org) with static analysis tool 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	2.6.38 — 6.1.129
linux	linux_kernel	6.2 — 6.6.78
linux	linux_kernel	6.7 — 6.12.14
linux	linux_kernel	6.13 — 6.13.3

References

Advisories & Patches

https://git.kernel.org/stable/c/250423300b4b0335918be187ef3cade248c06e6a https://git.kernel.org/stable/c/6438ef381c183444f7f9d1de18f22661cba1e946 https://git.kernel.org/stable/c/b9495a9109abc31d3170f7aad7d48aa64610a1a2 https://git.kernel.org/stable/c/f2bd0f1ab47822fe5bd699c8458b896c4b2edea1 https://git.kernel.org/stable/c/f3d80f34f58445355fa27b9579a449fb186aa64e

Other References

https://git.kernel.org/stable/c/58b1c6881081f5ddfb9a14dc241a74732c0f855c https://git.kernel.org/stable/c/7649937987fed51ed09985da4019d50189fc534e https://git.kernel.org/stable/c/8f41df5fd4c11d26e929a85f7239799641f92da7 https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html

Frequently Asked Questions

What is CVE-2025-21736? +

In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix possible int overflows in nilfs_fiemap() Since nilfs_bmap_lookup_contig() in nilfs_fiemap() calculates its result by being prepared to go through potentially maxblocks == INT_MAX blocks, the value in n may experience an overflow caused by left shift of blkbits. While it is extremely unlikely to occur, play it safe and cast right hand expression to wider type to mitigate the issue. Found by Linux Verification Center (linuxtesting.org) with static analysis tool SVACE. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21736? +

CVE-2025-21736 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-2025-21736? +

CVE-2025-21736 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-2025-21736? +

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-2025-21736