Actively Exploited — CISA KEV

CVE-2026-20128: Cisco Catalyst SD-WAN Manager High-Severity Vulnerability

Severity: High | CVSS 3.1: 7.5 | Published: 2026-02-25 | KEV Added: 2026-04-20

What is CVE-2026-20128?

A vulnerability in the Data Collection Agent (DCA) feature of Cisco Catalyst SD-WAN Manager could allow an unauthenticated, remote attacker to gain DCA user privileges on an affected system. This vulnerability is due to the presence of a credential file for the DCA user on an affected system. An attacker could exploit this vulnerability by sending a crafted HTTP request and reading the file that contains the DCA password from that affected system. A successful exploit could allow the attacker to access another affected system and gain DCA user privileges. Note: Cisco Catalyst SD-WAN Manager releases 20.18 and later are not affected by this vulnerability.

Technical Analysis

Weakness Classification

This vulnerability is classified as CWE-257.

Attack Vector Breakdown

  • Attack Vector: Local
  • Attack Complexity: High
  • Privileges Required: High
  • User Interaction: None
  • Scope: Changed
  • Confidentiality: High
  • Integrity: High
  • Availability: High

Impact Analysis

Exploitation requires local access to the target system, such as a local user session or a malicious file opened by a user. Successful exploitation can result in full confidentiality breach (complete data disclosure), complete integrity compromise (data modification or code execution), total availability loss (denial of service). Notably, the vulnerability's scope is changed, meaning exploitation can affect resources beyond the vulnerable component — for example, escaping a sandbox or container to impact the host system.

Exploitation Probability (EPSS): 0.07% chance of exploitation in the next 30 days (21th percentile). While the base probability may appear low, inclusion in CISA KEV confirms real-world exploitation is already occurring.

Is CVE-2026-20128 being exploited?

Yes. CVE-2026-20128 is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, restricted to CVEs with confirmed active exploitation in the wild. CISA added this vulnerability on 2026-04-20. Inclusion in KEV triggers the patching mandate under BOD 22-01 for U.S. federal civilian agencies, with a remediation deadline of 2026-04-23.

How to fix CVE-2026-20128

Download the fixed software release from the Cisco Software Center. For IOS/IOS XE, use the Cisco Software Checker to identify the specific fixed release. If upgrading is not immediately possible, apply the workaround or mitigation described in the Cisco Security Advisory (e.g. ACLs, disabling affected features). Check the Cisco Security Advisories page for the specific patch or update. CISA's Known Exploited Vulnerabilities catalog requires U.S. federal agencies to remediate this vulnerability by the due date shown below under Binding Operational Directive 22-01. Private organizations should treat KEV entries as priority-one patches because active exploitation has been confirmed in the wild.

Related Vulnerabilities

Other actively exploited vulnerabilities affecting Catalyst SD-WAN Manager or sharing the same weakness (CWE-257):

  • CVE-2026-20133 (Medium 6.5) [same product] — A vulnerability in Cisco Catalyst SD-WAN Software could allow an…
  • CVE-2026-20182 (Critical 10.0) [same vendor] — May 2026: This security advisory provides the details and fix information for…
  • CVE-2026-20122 (Medium 5.4) [same vendor] — A vulnerability in the API of Cisco Catalyst SD-WAN Manager could allow an…
  • CVE-2026-20131 (Critical 10.0) [same vendor] — A vulnerability in the web-based management interface of Cisco Secure Firewall…
  • CVE-2022-20775 (High 7.8) [same vendor] — A vulnerability in the CLI of Cisco SD-WAN Software could allow an…

Frequently asked questions

Is CVE-2026-20128 critical?

CVE-2026-20128 has a CVSS 3.1 base score of 7.5 — High severity. It should be treated as a priority patch, especially given the active exploitation confirmed by CISA.

Is CVE-2026-20128 being actively exploited?

Yes — CISA added CVE-2026-20128 to the Known Exploited Vulnerabilities catalog on 2026-04-20. Inclusion in KEV means CISA has confirmed in-the-wild exploitation.

How do I patch CVE-2026-20128?

Apply the security update from Cisco for Catalyst SD-WAN Manager. Federal agencies must remediate by 2026-04-23 under BOD 22-01. Refer to the Cisco Security Advisories for the official patch.

What type of vulnerability is CVE-2026-20128?

CVE-2026-20128 is classified under CWE-257.

What is the CVSS score for CVE-2026-20128?

CVE-2026-20128 has a CVSS 3.1 base score of 7.5, classifying it as High severity. The attack vector is Local, attack complexity is High, and non-zero privileges are required.