LiveActive security incident?Get immediate response
CVE Record

CVE-2020-3284: Cisco IOS XR Software Enhanced Preboot eXecution Environment Unsigned Code Execution Vulnerability

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.

HighCVSS 8.1Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Cisco IOS XR devices can be exposed during network boot if their PXE boot path is subverted. An attacker who controls or convincingly impersonates the PXE boot server could cause unsigned code to run before the device fully boots. This is high impact but requires specific boot infrastructure conditions.

Executive priority

Prioritize remediation for core routing and network infrastructure using IOS XR. The business risk is severe device compromise during boot, but exposure depends on PXE boot use and management network control.

Technical view

The flaw is in the enhanced PXE boot loader for Cisco IOS XR 64-bit Software. Internal commands used while loading a network boot image are not properly verified, enabling unsigned code execution during PXE boot. Cisco states remediation requires upgrading both IOS XR Software and BIOS.

Likely exposure

Organizations running affected Cisco IOS XR 64-bit platforms, especially where management interfaces and PXE boot infrastructure are reachable or weakly controlled.

Exploitation context

The source bundle does not show CISA KEV listing or active exploitation. Exploitation requires compromising or impersonating PXE boot infrastructure during the boot process, matching the high attack complexity in CVSS.

Researcher notes

Key unknowns are exact affected versions and platform coverage in the provided bundle. Validate against Cisco’s advisory rather than assuming all IOS XR deployments are affected. Do not treat this as confirmed exploited without separate KEV or vendor evidence.

Mitigation direction

  • Review Cisco’s advisory and Fixed Software section for affected platform details.
  • Upgrade Cisco IOS XR Software to a fixed release.
  • Upgrade the BIOS as Cisco requires for this vulnerability.
  • Follow any additional BIOS installation steps documented by Cisco.
  • Protect management networks and PXE boot infrastructure from untrusted access.

Validation and detection

  • Inventory Cisco IOS XR 64-bit devices and hardware platforms.
  • Check whether devices rely on enhanced PXE boot over management interfaces.
  • Confirm both IOS XR Software and BIOS versions are fixed.
  • Review PXE boot server administration and change history for unexpected modifications.
  • Document remaining devices where affected versions cannot be confirmed.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · medium confidence lookup

CWE-284: Authorization and privilege behavior lookup

Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2020-3284 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
8.1 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.1CVSS 3.0HighCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

8.1High
CVSS 3.0 vector shape for CVE-2020-3284Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco IOS XR Softwaren/aListed
Weakness

CWE details

CWE-284

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-284 · source CWE mapping

Improper Access Control

Improper Access Control represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs