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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 17 Nov 2021.
Trusted Firmware MOperating system · Trustedfirmware

CVE-2021-27562

MEDIUM · 5.5 CVSS v3.1 Published 2021-05-25
Fix available
A fix is available. Upgrade to after 1.2.0 or later.
See remediation →
96/100
Remediation priority · Urgent
In the wild 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
In Arm Trusted Firmware M through 1.2, the NS world may trigger a system halt, an overwrite of secure data, or the printing out of secure data when calling secure functions under the NSPE handler mode.

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

In Arm Trusted Firmware M through 1.2, the Non-Secure World (NS world) can trigger improper behavior when calling secure functions under NSPE handler mode, potentially causing system halt, overwriting secure data, or exposing secure data through printing. This indicates a failure in secure/non-secure world boundary enforcement in the firmware's secure function call interface.

MitigationUpdate to the patched version of Arm Trusted Firmware M (1.2+). Review and validate secure function call paths from the NS world to ensure proper boundary enforcement and input validation are in place.

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
Trusted Firmware MOperating system
Affected:<= 1.2.0

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. Identify Trusted Firmware M installation
    Check system firmware documentation or boot logs for 'Arm Trusted Firmware M' or 'TF-M' presence. On systems using TF-M, the firmware version is typically visible in early boot logs or via debug interfaces.
    Affected if The system does not use Arm Trusted Firmware M as its secure firmware - if another secure firmware is used, this CVE does not apply.
  2. Determine TF-M version
    Locate the TF-M version string in boot logs, firmware binary metadata, or build information. The version format is typically 'TF-M vX.Y.Z' or similar. Compare against the affected range <= 1.2.0.
    Affected if The installed version is 1.2.0 or earlier. Versions 1.3.0 and later contain the fix.
  3. Check NSPE handler mode configuration
    Review TF-M configuration files (platform_def.h, tfm_config.h) and build options for NSPE (Non-Secure Processing Environment) handler mode. This mode is enabled via specific build flags or platform configuration.
    Affected if NSPE handler mode is enabled and secure function calls are being made from Non-Secure World to Secure World.
  4. Inspect secure function call interface
    Examine the secure function call path implementation in TF-M, specifically the SPM (Secure Partition Manager) interface handling calls from NSPE. Look for missing boundary enforcement or input validation in the secure gateway veneer.
    Affected if The system makes secure function calls from NSPE handler mode and lacks proper boundary enforcement checks in the call interface.

A system is affected if it runs Arm Trusted Firmware M version 1.2.0 or earlier AND utilizes NSPE handler mode to invoke secure functions from the Non-Secure World, as this is the specific configuration where the boundary enforcement failure occurs.

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 a release after 1.2.0
Interim mitigation

Update to the patched version of Arm Trusted Firmware M (1.2+). Review and validate secure function call paths from the NS world to ensure proper boundary enforcement and input validation are in place.

Recommended fix High confidence

TF-M 1.2.1 or later

  1. 1. Identify the current version of Trusted Firmware M in your deployment by checking the version.h file or build artifacts
  2. 2. Navigate to the Trusted Firmware M official repository at git.trustedfirmware.org
  3. 3. Obtain the fixed release version (TF-M 1.2.1 or later) from the official releases or tags
  4. 4. Update your build system to use the fixed version by pulling the new release or checking out the appropriate tag
  5. 5. Rebuild the Trusted Firmware M binary with the updated source code
  6. 6. Verify the build completes without errors
  7. 7. Flash the newly built TF-M binary to the target device, ensuring secure world firmware is updated
  8. 8. Test that the device boots properly and secure functions operate correctly
Caveat Carefully review any API changes between your current version and 1.2.1; ensure dependent secure application code is compatible with the updated TF-M API

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

Fix this in Trusted Firmware M Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,760
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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-2021-27562 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