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Op TeeOperating system · Trustedfirmware

CVE-2021-36133

HIGH · 7.1 CVSS v3.1 Published 2021-12-07
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
73/100
Remediation priority · Elevated
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
The OPTEE-OS CSU driver for NXP i.MX SoC devices lacks security access configuration for several models, resulting in TrustZone bypass because the NonSecure World can perform arbitrary memory read/write operations on Secure World memory. This involves a DMA capable peripheral.

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

The OPTEE-OS CSU driver for NXP i.MX SoC devices lacks security access configuration for certain models, enabling a DMA-capable peripheral to allow the NonSecure World to perform arbitrary memory read/write operations on Secure World memory, resulting in a TrustZone bypass.

MitigationUpdate the OPTEE-OS CSU driver to enforce proper security access configuration for affected i.MX models, ensuring DMA-capable peripherals cannot access Secure World memory from the NonSecure World.

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
Op TeeOperating system
Affected:all versions

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
None

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

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 the hardware platform
    Check the system hardware specifications or use commands like 'cat /proc/cpuinfo', 'dmidecode', or check boot logs to identify if the device uses an NXP i.MX SoC family processor
    Affected if The device is an NXP i.MX SoC (such as i.MX6, i.MX7, or i.MX8 series)
  2. Verify OPTEE-OS is present
    Check for OPTEE-OS by examining /proc/tee/ listing, checking for optee kernel modules via 'lsmod | grep optee', or reviewing boot logs for 'OP-TEE' or 'trusted execution environment' initialization messages
    Affected if OPTEE-OS is running on the device
  3. Check CSU driver configuration
    Examine the device tree or firmware configuration for CSU (Central Security Unit) settings. Look for 'csu' or 'security-config' nodes in the device tree blob (DTB) or check /sys/firmware/devicetree/ for csu-related entries
    Affected if The CSU security access configuration is missing or improperly set for DMA-capable peripherals
  4. Verify DMA peripheral access controls
    Review memory mapping and DMA configuration in the device tree or firmware. Check if DMA-capable peripherals have properly configured Stream IDs (SID) or region access controls that prevent NonSecure access to Secure World memory
    Affected if DMA-capable peripherals lack proper Stream ID filtering or security region restrictions to isolate Secure World memory from NonSecure access
  5. Confirm TrustZone isolation status
    Check if Secure World memory regions are protected from NonSecure access by reviewing memory layout via 'cat /proc/meminfo' with secure flags, examining optee logs for security configuration, or using 'teeinfo' or 'tee-supplicant' to query TEE security state
    Affected if NonSecure World can access Secure World memory regions or TrustZone isolation is not enforced

The environment is affected if it runs OPTEE-OS on an NXP i.MX SoC device where the CSU driver lacks proper security access configuration to block DMA-capable peripherals from accessing Secure World memory from the NonSecure World.

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

Update the OPTEE-OS CSU driver to enforce proper security access configuration for affected i.MX models, ensuring DMA-capable peripherals cannot access Secure World memory from the NonSecure World.

Fix this in Op Tee Scoped from the published advisory
  • Consultation6.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA6.0 h
40.0 hours of engineering $6,960
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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-2021-36133 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
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