CVE-2021-1353

Cisco StarOS IPv4 Denial of Service Vulnerability

HIGH
8.6
CVSS Score
Published: January 20, 2021 at 08:00 PM UTC
Updated: June 17, 2026 at 03:31 AM UTC
5 products affected across 1 vendorStarosVirtualized Packet Core Single InstanceAsr 5000

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Severity
HIGH8.6
Exploit prediction
EPSS 1%
SSVC
No known exploit

Description

A vulnerability in the IPv4 protocol handling of Cisco StarOS could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory leak that occurs during packet processing. An attacker could exploit this vulnerability by sending a series of crafted IPv4 packets through an affected device. A successful exploit could allow the attacker to exhaust the available memory and cause an unexpected restart of the npusim process, leading to a DoS condition on the affected device.

Affected

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

v < 21.22.0
Affected range stops below 21.22.0, so it looks safe — our inference, not a vendor statement
cisco-asr-5000 (environment) · cisco-asr-5500 (environment) · cisco-asr-5700 (environment)
All versions
All versions
All versions

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
CHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-401

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