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Linux KernelOperating system · Linux

CVE-2026-53015

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 6.12.91 / 6.18.33 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available 8 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In the Linux kernel's erofs filesystem, the logical cluster number (lcn) variable was incorrectly typed as `unsigned long` or `unsigned int`, which is only 32 bits wide on 32-bit platforms. When performing `(lcn << lclusterbits)` to calculate cluster offsets, the result gets truncated at 4 GiB, potentially causing incorrect data access or file system corruption when handling files/clusters beyond 4 GiB on 32-bit systems.

MitigationThis is a kernel bug fix requiring a type change from 32-bit to 64-bit (u64). No end-user mitigation is available; organizations should apply kernel updates when available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.3, < 6.12.91>= 6.13, < 6.18.33>= 6.19, < 7.0.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check kernel architecture
    Run `uname -m` or `getconf LONG_BIT` to determine if running a 32-bit kernel (i386/i686 indicates 32-bit, x86_64 indicates 64-bit)
    Affected if The system runs a 32-bit kernel (i386/i686). The truncation bug only affects 32-bit platforms where 'unsigned long' is 32 bits.
  2. Check kernel version
    Run `uname -r` or `cat /proc/version` to get the kernel version
    Affected if The kernel version falls within: >= 5.3 and < 6.12.91, OR >= 6.13 and < 6.18.33, OR >= 6.19 and < 7.0.10
  3. Check if erofs filesystem is available
    Run `cat /proc/filesystems | grep erofs` or check if erofs is listed in available filesystem types
    Affected if The erofs filesystem is supported and available on the system
  4. Check for mounted erofs filesystems
    Run `mount | grep -E 'erofs|type.erofs'` or `findmnt -t erofs` to list any erofs mounts
    Affected if Any erofs filesystems are currently mounted and in use
  5. Identify large files on erofs mounts
    For each erofs mount point, use `find <mountpoint> -type f -size +4G` to locate files larger than 4 GiB
    Affected if Files or clusters larger than 4 GiB exist on any mounted erofs filesystem

A system is affected if it runs a 32-bit Linux kernel with a version in the affected ranges, uses the erofs filesystem, and handles files/clusters exceeding 4 GiB, causing potential incorrect data access or filesystem corruption.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.12.91 / 6.18.33 / 7.0.10 or later
Fixed in 6.12.916.18.337.0.10
Vendor patch git.kernel.org →
Interim mitigation

This is a kernel bug fix requiring a type change from 32-bit to 64-bit (u64). No end-user mitigation is available; organizations should apply kernel updates when available.

Recommended fix High confidence

6.12.91 or 6.18.33 or 7.0.10 (depending on current branch)

  1. Identify your current kernel version using `uname -r`
  2. Determine which version branch you are on (5.3-6.12.x, 6.13-6.18.x, or 6.19-7.0.x)
  3. Upgrade to the next fixed version in your branch: 6.12.91 for 5.3-6.12.x, 6.18.33 for 6.13-6.18.x, or 7.0.10 for 6.19-7.0.x
  4. Verify the upgrade using `uname -r` after rebooting
Caveat Standard kernel upgrade - ensure bootloader configuration and kernel modules are compatible

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation2.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,440
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Scan for this in your stack

Free · runs locally
dbcve dependency scanner

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-53015 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data