Ios Xe Rom MonitorOperating system · Cisco
CVE-2021-1452
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 ROM Monitor (ROMMON) of Cisco IOS XE Software for Cisco Catalyst IE3200, IE3300, and IE3400 Rugged Series Switches, Cisco Catalyst IE3400 Heavy Duty Series Switches, and Cisco Embedded Services 3300 Series Switches could allow an unauthenticated, physical attacker to execute unsigned code at system boot time. This vulnerability is due to incorrect validations of specific function arguments passed to a boot script when specific ROMMON variables are set. An attacker could exploit this vulnerability by setting malicious values for a specific ROMMON variable. A successful exploit could allow the attacker to execute unsigned code and bypass the image verification check during the secure boot process of an affected device. To exploit this vulnerability, the attacker would need to have unauthenticated, physical access to the device or obtain privileged access to the root shell on the device.
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 Cisco IOS XE ROMMON allows unauthenticated physical attackers to execute unsigned code at boot by setting malicious values to specific ROMMON variables, bypassing the secure boot image verification. The flaw stems from incorrect validation of function arguments passed to boot scripts when specific ROMMON variables are configured.
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
Ios Xe Rom MonitorOperating system
<= 7.0CVSS 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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Access ROMMON and retrieve versionConnect to the device console, then reboot the device and press Break key during boot to enter ROMMON prompt. Once in ROMMON, use the 'show version' or 'version' command to display the ROMMON firmware version.Affected if ROMMON version displayed is 7.0 or lower (any version <= 7.0)
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Verify IOS XE version as secondary contextFrom normal IOS XE prompt (not ROMMON), run 'show version' to display the running IOS XE software version. Note the ROMMON version may be displayed in this output as well.Affected if The device runs Cisco IOS XE with ROMMON version <= 7.0 shown in the output
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Confirm physical access exposureReview physical security controls around the affected device. Verify who has console access and whether the ROMMON break key sequence can be triggered during boot.Affected if Device is physically accessible to unauthenticated users who could access the ROMMON prompt
The device is affected if ROMMON version is 7.0 or lower and the device is physically accessible to enable an attacker to enter ROMMON and configure malicious variables.
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 the Cisco patch for CVE-2021-1452 and enforce physical security controls on affected devices to prevent unauthorized access to console/ROMMON interfaces.
Fix this in Ios Xe Rom Monitor
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-1452 — 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-2021-1452 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
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