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CVE-2026-53015: erofs: unify lcn as u64 for 32-bit platforms

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-24 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: erofs: unify lcn as u64 for 32-bit platforms As sashiko reported [1], `lcn` was typed as `unsigned long` (or `unsigned int` sometimes), which is only 32 bits wide on 32-bit platforms, which causes `(lcn << lclusterbits)` to be truncated at 4 GiB. In order to consolidate the logic, just use `u64` consistently around the codebase. [1] https://sashiko.dev/r/20260420034612.1899973-1-hsiangkao%40linux.alibaba.com

Affected products

• Linux kernel: from 5.3 before 6.12.91; from 6.13 before 6.18.33; from 6.19 before 7.0.10 — fixed in 6.12.91, 6.18.33, 7.0.10
• Linux: 5.3 — fixed in 7.1

How to fix

Upgrade to a fixed version: Linux kernel 6.12.91, 6.18.33, 7.0.10; Linux 7.1. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/18f9f3ddbf2ed6d245a4c6f91c51f7248f8a982c
• https://git.kernel.org/stable/c/2d8c7edcb661812249469f4a5b62e9339118846f
• https://git.kernel.org/stable/c/4fc9b12e43a3f19a01a8fb61f7961be79de20253
• https://git.kernel.org/stable/c/582b0bf201157632cb5474c885989a6ebda46521
• https://git.kernel.org/stable/c/858e4d98a86adf34584767388deb6c9b217f70c5
• https://git.kernel.org/stable/c/d142250132454bf86cba87018fb2d29c482dacd6

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