Is CVE-2021-1353 actively exploited?

No active exploitation of CVE-2021-1353 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-1353 be exploited remotely?

Yes. CVE-2021-1353 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-1353?

CVE-2021-1353 has a CVSS score of 8.6 (HIGH).

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HIGH

CVE-2021-1353

CWE-401Published: January 20, 2021· Updated: Jun 17, 2026

8.6

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-1353 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 8.6.

The vulnerability has a "Changed" scope, meaning successful exploitation can impact components beyond the vulnerable component itself — such as the host operating system or adjacent services.