CVE-2024-20397
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 · uneditedA vulnerability in the bootloader of Cisco NX-OS Software could allow an unauthenticated attacker with physical access to an affected device, or an authenticated, local attacker with administrative credentials, to bypass NX-OS image signature verification. This vulnerability is due to insecure bootloader settings. An attacker could exploit this vulnerability by executing a series of bootloader commands. A successful exploit could allow the attacker to bypass NX-OS image signature verification and load unverified software.
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 confidenceA vulnerability in the Cisco NX-OS bootloader allows attackers to bypass image signature verification through insecure bootloader settings. Physical access or administrative credentials enable exploitation via a series of bootloader commands, potentially allowing unverified software to load on affected devices.
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
- Physical
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify NX-OS versionExecute 'show version' or 'show install all' command in NX-OS CLI to retrieve the running software versionAffected if The installed NX-OS version falls within the vulnerable version range for this CVE and has not been patched
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Check bootloader secure boot configurationAccess the bootloader prompt (typically via console during boot) and run 'show secureboot' or 'show boot' commands to inspect signature verification settingsAffected if Secure boot or image signature verification is disabled, or the bootloader shows insecure configuration values
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Verify image signature verification statusIn NX-OS CLI, run 'show secureboot status' or 'show bootvgpeek' if available, or check 'show system redundancy status' for boot integrity detailsAffected if Image signature verification is not enforced or returns a disabled/failed status
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Inspect boot logs for tampering indicatorsReview boot logs via 'show logging' or console output during boot for unexpected bootloader entries, boot menu changes, or signature verification bypass messagesAffected if Boot logs show evidence of unauthorized bootloader access, disabled verification, or loading of unverified images
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Confirm physical and administrative access controlsReview whether the device console is in a secured location and verify that administrative credentials have not been compromisedAffected if Physical access is unrestricted or administrative credentials are known to have been exposed, enabling bootloader command execution
The device is affected if it runs a vulnerable NX-OS version and has insecure bootloader settings with signature verification disabled or bypassed, especially if physical access or administrative credentials could allow an attacker to access bootloader commands.
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 dataApply Cisco-provided patches and configure secure/verified boot settings in the bootloader to enforce NX-OS image signature verification. Restrict physical access to network infrastructure and follow least-privilege principles for administrative accounts.
- Consultation6.0 h
- Implementation12.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-20397 — 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-2024-20397 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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- 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