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A9k Rsp880 Se FirmwareOperating system · Cisco

CVE-2020-3284

CRITICAL · 9.8 CVSS v3.1 Published 2020-11-06
Fix available
A fix is available. Upgrade to 1.12 / 1.21 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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
A vulnerability in the enhanced Preboot eXecution Environment (PXE) boot loader for Cisco IOS XR 64-bit Software could allow an unauthenticated, remote attacker to execute unsigned code during the PXE boot process on an affected device. The PXE boot loader is part of the BIOS and runs over the management interface of hardware platforms that are running Cisco IOS XR Software only. The vulnerability exists because internal commands that are issued when the PXE network boot process is loading a software image are not properly verified. An attacker could exploit this vulnerability by compromising the PXE boot server and replacing a valid software image with a malicious one. Alternatively, the attacker could impersonate the PXE boot server and send a PXE boot reply with a malicious file. A successful exploit could allow the attacker to execute unsigned code on the affected device. Note: To fix this vulnerability, both the Cisco IOS XR Software and the BIOS must be upgraded. The BIOS code is included in Cisco IOS XR Software but might require additional installation steps. For further information, see the Fixed Software section of this advisory.

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 confidence

A vulnerability in the enhanced PXE boot loader for Cisco IOS XR 64-bit Software allows an unauthenticated remote attacker to execute unsigned code during the PXE boot process. The vulnerability exists because internal commands issued during PXE network boot are not properly verified, enabling code injection via a compromised or impersonated PXE boot server sending malicious software images over the management interface.

MitigationUpgrade both Cisco IOS XR Software and the BIOS to fixed versions. The BIOS code is included in the IOS XR Software release but may require additional installation steps beyond the standard software upgrade.

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
A9k Rsp880 Se FirmwareOperating system
Affected:< 10.65
Ios XrOperating system
Affected:< 6.5.2< 7.2.1>= 7.0.0, < 7.0.2< 6.6.25< 1.21< 1.12
A9k Rsp880 Tr FirmwareOperating system
Affected:< 10.65
A99 Rp2 Se FirmwareOperating system
Affected:< 14.35
A99 Rp2 Tr FirmwareOperating system
Affected:< 14.35
A99 Rsp Se FirmwareOperating system
Affected:< 16.14
A99 Rsp Tr FirmwareOperating system
Affected:< 16.14
A9k Rsp880 Lt Se FirmwareOperating system
Affected:< 17.34

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify the IOS XR version
    Execute 'show version' or 'admin show version' on the device to retrieve the installed Cisco IOS XR software version
    Affected if The displayed version falls within the affected ranges: < 6.5.2, < 7.2.1, >= 7.0.0 and < 7.0.2, < 6.6.25, < 1.21, or < 1.12
  2. Check the router model and firmware version
    Execute 'show diag' or 'admin show diag' to identify the router model (A9k Rsp880, A99 Rsp, A99 Rp2) and its firmware version
    Affected if The router model is A9k Rsp880 Se/Tr/Lt, A99 Rp2 Se/Tr, or A99 Rsp Se/Tr with firmware version below 10.65, 14.35, or 16.14 respectively
  3. Verify management interface status
    Execute 'show interface mgmtEth 0/RP0/CPU0/0' or 'show ip interface brief | include Management' to check if the management interface is configured and active
    Affected if The management interface is up and accessible, as PXE boot occurs over this interface
  4. Confirm PXE boot configuration
    Execute 'show boot-var' or check the boot configuration with 'show running-config | include boot' to see if PXE boot is configured as a boot source
    Affected if PXE boot is enabled as a boot option, making the device vulnerable to code injection from a malicious PXE server

A device is affected if it runs a Cisco IOS XR version within the affected ranges AND has the management interface enabled with PXE boot capability configured.

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 1.12 / 1.21 / 6.5.2 or later
Fixed in 1.121.216.5.2
Interim mitigation

Upgrade both Cisco IOS XR Software and the BIOS to fixed versions. The BIOS code is included in the IOS XR Software release but may require additional installation steps beyond the standard software upgrade.

Recommended fix High confidence

IOS XR 7.0.2+/7.2.1+/6.5.2+/6.6.25 with corresponding BIOS: A9k Rsp880 10.65+, A99 Rp2 14.35+, A99 Rsp 16.14+, A9k Rsp880 Lt Se 17.34+

  1. 1. Identify the specific hardware platform (A9k Rsp880, A99 Rp2, A99 Rsp, etc.) and current firmware version using 'show version' or 'admin show version' commands.
  2. 2. Download the appropriate fixed IOS XR software release from Cisco (7.0.2+, 7.2.1+, 6.5.2+, or 6.6.25+ depending on your current train).
  3. 3. Download the corresponding fixed BIOS/firmware image: A9k Rsp880 to 10.65+, A99 Rp2 to 14.35+, A99 Rsp to 16.14+, A9k Rsp880 Lt Se to 17.34+.
  4. 4. Upgrade the IOS XR software using the standard install procedure (e.g., 'install add' and 'install activate' commands).
  5. 5. After IOS XR upgrade, apply the BIOS/firmware update - this may require additional installation steps as noted in the Cisco advisory.
  6. 6. Verify both the IOS XR version and BIOS firmware version meet the minimum fixed versions after upgrade.
  7. 7. Verify the PXE boot process now properly verifies code signatures before execution.
Caveat Both IOS XR software and BIOS must be upgraded together; BIOS update may require device reload and additional installation steps beyond standard IOS XR upgrade

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

Fix this in A9k Rsp880 Se Firmware Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2020-3284 in production — separate from our analysis above.

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What this is

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