CVE-2021-1243

Cisco IOS XR Software SNMP Management Plane Protection ACL Bypass Vulnerability

HIGH
7.5
CVSS Score
Published: February 4, 2021 at 04:35 PM UTC
Updated: June 17, 2026 at 03:31 AM UTC
1 product affected across 1 vendorIOS Xr

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Severity
HIGH7.5
Exploit prediction
EPSS 1%
SSVC
No known exploit

Description

A vulnerability in the Local Packet Transport Services (LPTS) programming of the SNMP with the management plane protection feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to allow connections despite the management plane protection that is configured to deny access to the SNMP server of an affected device. This vulnerability is due to incorrect LPTS programming when using SNMP with management plane protection. An attacker could exploit this vulnerability by connecting to an affected device using SNMP. A successful exploit could allow the attacker to connect to the device on the configured SNMP ports. Valid credentials are required to execute any of the SNMP requests.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

7.0.0 ≤ v < 7.0.26.1.1 < v < 6.6.46.7.17.0.117.1.07.2.0
Affected range stops below 6.6.4, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.0.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-284NVD-CWE-Other

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