CVE-2026-53015: erofs: unify lcn as u64 for 32-bit platforms
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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Update the erofs code to consistently use `u64` for `lcn` (instead of `unsigned long`/`unsigned int`) so that expressions like `(lcn << lclusterbits)` are not truncated on 32-bit platforms.
Linux kernel (erofs) lcn type = u64
Event History
Frequently Asked Questions
What is the severity of CVE-2026-53015?
CVE-2026-53015 has a medium severity rating of 5.5.
What software is affected by CVE-2026-53015?
CVE-2026-53015 affects the Linux kernel, specifically the erofs file system.
How does CVE-2026-53015 impact 32-bit platforms?
CVE-2026-53015 causes truncation issues due to the incorrect data type of 'lcn' on 32-bit platforms.
How do I fix CVE-2026-53015?
To fix CVE-2026-53015, update your Linux kernel to the latest version that resolves this vulnerability.
What is the nature of the vulnerability in CVE-2026-53015?
CVE-2026-53015 is related to a type inconsistency in the Linux kernel that affects how 'lcn' is handled on 32-bit systems.