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Integer OverflowWeakness · CWE-190

CVE-2026-20753

HIGH · 8.7 CVSS v4.0 Published 2026-05-12
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
89/100
Remediation priority · High
Zero-click

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
Integer overflow in the UEFI firmware for the Slim Bootloader may allow an escalation of privilege. System software adversary with a privileged user combined with a low complexity attack may enable local code execution. This result may potentially occur via local access when attack requirements are present without special internal knowledge and requires no user interaction. The potential vulnerability may impact the confidentiality (high), integrity (high) and availability (high) of the vulnerable system, resulting in subsequent system confidentiality (high), integrity (high) and availability (high) impacts.

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

Integer overflow vulnerability in UEFI firmware for Slim Bootloader allows a local attacker with privileged user access to achieve code execution and privilege escalation. The low-complexity attack requires no user interaction and results in complete compromise of system confidentiality, integrity, and availability.

MitigationApply the vendor-supplied firmware update for Slim Bootloader to patch the integer overflow; limit physical and local access to affected systems to reduce attack surface.

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

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
High
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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 Slim Bootloader is in use
    Check system firmware/boot information using 'dmidecode -s bios-version' or through UEFI shell 'ver' command, or check boot logs for 'Slim Bootloader' references
    Affected if Slim Bootloader is listed as the active firmware bootloader
  2. Retrieve firmware version
    Use tools like 'fwupdtool get-devices', 'dmidecode', or UEFI utility 'efibootmgr -v' to query the Slim Bootloader firmware version
    Affected if Version cannot be determined or is present (compare to any vendor-published fixed versions)
  3. Verify UEFI secure boot status
    Check secure boot status via 'mokutil --sb-state' or through UEFI setup configuration
    Affected if Secure boot is disabled and Slim Bootloader is active
  4. Check for physical/local privileged access
    Review system access controls and user privileges - the vulnerability requires a local attacker with privileged (administrator/root) access
    Affected if System has local privileged users and Slim Bootloader is present

System is affected if Slim Bootloader is the active UEFI firmware and the installed firmware version falls within the vulnerable range or cannot be verified against patched versions

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the vendor-supplied firmware update for Slim Bootloader to patch the integer overflow; limit physical and local access to affected systems to reduce attack surface.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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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-2026-20753 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