What’s Vulnerable › Vulnerabilities

CVE-2021-1353: Cisco StarOS IPv4 Denial of Service Vulnerability

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-01-20 · updated 2026-06-17
• Weakness: CWE-401

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 products

• Cisco StarOS: before 21.22.0 — fixed in 21.22.0
• Cisco Virtualized Packet Core-Single Instance: all versions

How to fix

Upgrade to a fixed version: Cisco StarOS 21.22.0. Check the vendor advisory for mitigations.

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr-mem-leak-dos-MTWGHKk3
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asr-mem-leak-dos-MTWGHKk3

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