Is CVE-2026-20004 actively exploited?

No active exploitation of CVE-2026-20004 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2026-20004 be exploited remotely?

Partially. CVE-2026-20004 requires adjacent network access (same network segment) to exploit.

What is the CVSS score of CVE-2026-20004?

CVE-2026-20004 has a CVSS score of 7.4 (HIGH).

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HIGH

CVE-2026-20004

CWE-771Published: March 25, 2026· Updated: Mar 26, 2026

7.4

CVSS v3.1

Official Description

A vulnerability in the TLS library of Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to exhaust the available memory of an affected device.

This vulnerability is due to improper management of memory resources during TLS connection setup. An attacker could exploit this vulnerability by repeatedly triggering the conditions that cause the memory increase. This could be done in a variety of ways, such as by repeatedly attempting Extensible Authentication Protocol (EAP) authentication when local EAP is enabled on an affected device or by using a machine-in-the-middle attack and resetting TLS connections between the affected device and other devices. A successful exploit could allow the attacker to exhaust the available memory on an affected device, resulting in an unexpected reload and a denial of service (DoS) condition.

NVD Source

Technical Analysis

CVE-2026-20004 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

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 7.4.

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.