CVE-2021-44850
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 · uneditedOn Xilinx Zynq-7000 SoC devices, physical modification of an SD boot image allows for a buffer overflow attack in the ROM. Because the Zynq-7000's boot image header is unencrypted and unauthenticated before use, an attacker can modify the boot header stored on an SD card so that a secure image appears to be unencrypted, and they will be able to modify the full range of register initialization values. Normally, these registers will be restricted when booting securely. Of importance to this attack are two registers that control the SD card's transfer type and transfer size. These registers could be modified a way that causes a buffer overflow in the ROM.
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 confidenceThe Xilinx Zynq-7000 SoC has a buffer overflow vulnerability in its ROM bootloader. Because the SD boot image header is unencrypted and unauthenticated before use, an attacker with physical access can modify the boot header on an SD card to manipulate SD card transfer type and size registers. This modification can trigger a buffer overflow in the ROM, allowing bypass of secure boot restrictions and modification of normally restricted registers.
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 dataall versionsall versionsall versionsall versionsall versionsall versionsall versionsall versionsCVSS 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
- Physical
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:P/AC:L/PR:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify the Zynq-7000 SoC model in useExamine the device documentation, BOM, or physically inspect the SoC markings to confirm it is one of: Z-7012s, Z-7014s, Z-7010, Z-7015, Z-7020, Z-7030, Z-7035, or Z-7045Affected if The device uses any of the listed Zynq-7000 variants
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Determine if the device boots from SD cardCheck the boot mode settings or boot pin configuration on the device to verify whether SD card boot is enabled as the primary or fallback boot sourceAffected if SD card boot mode is configured and active
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Verify the secure boot statusInspect the device boot configuration registers or secure boot settings via the Xilinx JTAG debugger, Vivado, or boot ROM configuration to determine if authenticated boot is enabledAffected if Secure boot (authenticated/encrypted boot images) is disabled or not enforced
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Assess physical access controls to the SD cardLocate the SD card slot on the device and evaluate whether an attacker with physical access could remove, modify, or replace the SD card without detection or obstructionAffected if The SD card is accessible without requiring specialized tools or breaching a secure enclosure
The device is affected if it uses any of the listed Zynq-7000 variants, boots from an SD card, and has secure boot disabled, combined with physical accessibility of the SD card slot.
Generated from the published advisory. Verify against your own configuration.
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 dataRemediate by implementing authenticated/encrypted boot images, enabling secure boot with hardware root of trust, and ensuring physical security of devices to prevent unauthorized SD card manipulation. If secure boot is not already enabled, enabling it would prevent this attack vector.
- Consultation8.0 h
- Implementation60.0 h
- Testing24.0 h
- Review / QA12.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $29,056.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-44850 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-44850 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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