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Linux KernelOperating system · Linux

CVE-2026-53020

HIGH · 7.8 CVSS v3.1 Published 2026-06-24
Fix available
A fix is available. Upgrade to 7.0.10 or later.
See remediation →
80/100
Remediation priority · High
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: um: Fix potential race condition in TLB sync During the TLB sync, we need to traverse and modify the page table, so we should hold the page table lock. Since full SMP support for threads within the same process is still missing, let's disable the split page table lock for simplicity.

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 · moderate confidence

A race condition exists in User Mode Linux (UML) during TLB sync operations where page table traversal and modification occurs without proper locking. The fix requires holding the page table lock during TLB sync, with the split page table lock being disabled due to incomplete SMP support for threads within the same process.

MitigationApply the kernel patch that adds proper page table locking during TLB sync operations in the UML subsystem.

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:>= 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
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Identify if running User Mode Linux (UML)
    Check the kernel config for CONFIG_UML=y or check /proc/cpuinfo for 'UML' or run 'uname -a' and look for 'um' in the platform field
    Affected if The system is not a UML guest (running as bare metal or other virtualization)
  2. Determine the kernel version
    Run 'uname -r' or 'cat /proc/version' to obtain the running kernel version number
    Affected if The kernel version is less than 6.19 or greater than or equal to 7.0.10 (outside the affected range 6.19 to < 7.0.10)
  3. Verify UML kernel configuration
    Check /boot/config-$(uname -r) or /proc/config.gz (if available) for CONFIG_UML=y and CONFIG_MMU=y settings related to UML
    Affected if CONFIG_UML is not enabled in the kernel configuration
  4. Check for UML-specific TLB operations
    Inspect /sys/kernel/debug/uml (if debugfs is mounted) or look for 'tlb_sync' in kernel logs via 'dmesg | grep -i tlb' for any warnings related to TLB operations in UML
    Affected if No UML TLB-related operations are present or observable in the environment

The environment is affected only if it is running User Mode Linux (UML) with a kernel version >= 6.19 and < 7.0.10 where the race condition during TLB sync can occur.

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 7.0.10 or later
Fixed in 7.0.10
Interim mitigation

Apply the kernel patch that adds proper page table locking during TLB sync operations in the UML subsystem.

Recommended fix High confidence

Linux Kernel 7.0.10

  1. Obtain Linux Kernel version 7.0.10 or later from the official kernel repository (git.kernel.org)
  2. Verify the current running kernel version using 'uname -r'
  3. Follow standard procedures for your distribution to install the new kernel (e.g., using distribution package manager or compiling from source)
  4. Reboot the system to load the fixed kernel
  5. Verify the new kernel version is running using 'uname -r'
Caveat Kernel upgrades may introduce changes to APIs or module compatibility; test in a staging environment before production deployment

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
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,540
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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-2026-53020 in production — separate from our analysis above.

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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