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Linux KernelOperating system · Linux

CVE-2026-53021

MEDIUM · 5.5 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 5.10.258 / 5.15.209 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click 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: scsi: target: core: Fix integer overflow in UNMAP bounds check sbc_execute_unmap() checks LBA + range does not exceed the device capacity, but does not guard against LBA + range wrapping around on 64-bit overflow. Add an overflow check matching the pattern already used for WRITE_SAME in the same file.

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

Integer overflow vulnerability in sbc_execute_unmap() within the Linux kernel's SCSI target subsystem. The function validates that LBA + range does not exceed device capacity but fails to prevent 64-bit integer overflow where LBA + range wraps around, potentially allowing out-of-bounds memory access. The fix adds an overflow check following the same pattern already implemented for WRITE_SAME in the same file.

MitigationApply the kernel patch that adds overflow validation to prevent LBA + range from wrapping on 64-bit overflow, as the vulnerability has been resolved in the upstream kernel.

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:>= 3.10, < 5.10.258>= 5.11, < 5.15.209>= 5.16, < 6.1.175>= 6.2, < 6.6.141>= 6.7, < 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 version against affected ranges
    Run 'uname -r' or 'cat /proc/version' to get the installed kernel version. Compare against: < 5.10.258, 5.11-5.15.209, 5.16-6.1.175, 6.2-6.6.141, 6.7-6.12.91, 6.13-6.18.33, 6.19-7.0.10
    Affected if The installed kernel version falls within any of the affected version ranges
  2. Verify SCSI target subsystem is loaded
    Check if the SCSI target module is active by running 'lsmod | grep target' or checking for /sys/kernel/config/target/ directory existence
    Affected if The SCSI target subsystem (target_core_mod) is loaded and active, as sbc_execute_unmap() is only invoked in this context
  3. Confirm UNMAP command support is enabled
    Check if the system uses thin-provisioned LUNs or SCSI UNMAP by examining target configuration files in /etc/target/ or running 'targetcli ls' if targetcli is installed
    Affected if The system exposes thin-provisioned SCSI logical units that accept UNMAP commands, triggering the vulnerable code path

If the kernel version is in an affected range AND the SCSI target subsystem with UNMAP-capable LUNs is in use, the environment is vulnerable to the integer overflow.

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 5.10.258 / 5.15.209 / 6.1.175 or later
Fixed in 5.10.2585.15.2096.1.175
Interim mitigation

Apply the kernel patch that adds overflow validation to prevent LBA + range from wrapping on 64-bit overflow, as the vulnerability has been resolved in the upstream kernel.

Recommended fix High confidence

6.6.141 (or later stable in your kernel branch)

  1. 1. Identify the current running kernel version using `uname -r`
  2. 2. Determine which kernel branch (5.10.x, 5.11-5.15.x, 5.16-6.1.x, or 6.2-6.6.x) the system is running
  3. 3. For systems on 5.10.x branch: upgrade to kernel version 5.10.258 or later
  4. 4. For systems on 5.11-5.15.x branch: upgrade to kernel version 5.15.209 or later
  5. 5. For systems on 5.16-6.1.x branch: upgrade to kernel version 6.1.175 or later
  6. 6. For systems on 6.2-6.6.x branch: upgrade to kernel version 6.6.141 or later
  7. 7. Apply the kernel upgrade via distribution package manager (e.g., apt-get dist-upgrade, yum update, or dnf upgrade)
  8. 8. Reboot the system to load the patched kernel

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

Fix this in Linux Kernel Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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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-2026-53021 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