Cisco Secure Web Appliance up to 15.5.1-002 Dynamic Vectoring/Streaming Engine code download

Summaryinfo

A vulnerability was found in Cisco Secure Web Appliance. It has been classified as problematic. Affected by this issue is some unknown functionality of the component Dynamic Vectoring/Streaming Engine. The manipulation leads to code download. This vulnerability is traded as CVE-2026-20056. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Cisco Secure Web Appliance. This issue affects an unknown code block of the component Dynamic Vectoring/Streaming Engine. The manipulation with an unknown input leads to a code download vulnerability. Using CWE to declare the problem leads to CWE-494. The product downloads source code or an executable from a remote location and executes the code without sufficiently verifying the origin and integrity of the code. Impacted is integrity. The summary by CVE is:

A vulnerability in the Dynamic Vectoring and Streaming (DVS) Engine implementation of Cisco AsyncOS Software for Cisco Secure Web Appliance could allow an unauthenticated, remote attacker to bypass the anti-malware scanner, allowing malicious archive files to be downloaded. This vulnerability is due to improper handling of certain archive files. An attacker could exploit this vulnerability by sending a crafted archive file, which should be blocked, through an affected device. A successful exploit could allow the attacker to bypass the anti-malware scanner and download malware onto an end user workstation. The downloaded malware will not automatically execute unless the end user extracts and launches the malicious file. 

It is possible to read the advisory at sec.cloudapps.cisco.com. The identification of this vulnerability is CVE-2026-20056 since 10/08/2025. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/07/2026). The attack technique deployed by this issue is T1495 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 298243 (Cisco Secure Web Appliance Real-Time Scanning Archive File Bypass (cisco-sa-wsa-archive-bypass-Scx2e8zF)), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (298243). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• Cisco

Name

• Secure Web Appliance

Version

• 11.8.0-414
• 11.8.0-429
• 11.8.0-453
• 11.8.1-023
• 11.8.3-018
• 11.8.3-021
• 11.8.4-004
• 12.0.1-268
• 12.0.1-334
• 12.0.2-004
• 12.0.2-012
• 12.0.3-005
• 12.0.3-007
• 12.0.4-002
• 12.0.5-011
• 12.5.1-011
• 12.5.1-043
• 12.5.2-007
• 12.5.2-011
• 12.5.3-002
• 12.5.4-005
• 12.5.4-011
• 12.5.5-004
• 12.5.5-005
• 12.5.5-008
• 12.5.6-008
• 14.0.1-014
• 14.0.1-040
• 14.0.1-053
• 14.0.1-503
• 14.0.2-012
• 14.0.3-014
• 14.0.4-005
• 14.0.5-007
• 14.1.0-032
• 14.1.0-041
• 14.1.0-047
• 14.5.0-498
• 14.5.0-537
• 14.5.0-673
• 14.5.1-008
• 14.5.1-016
• 14.5.1-510
• 14.5.1-607
• 14.5.2-011
• 14.5.3-033
• 15.0.0-322
• 15.0.0-355
• 15.0.1-004
• 15.1.0-287
• 15.2.0-116
• 15.2.0-164
• 15.2.1-011
• 15.2.2-009
• 15.2.3-007
• 15.2.4-022
• 15.5.0-566
• 15.5.0-574
• 15.5.0-710
• 15.5.1-002

License

• commercial

Website

• Vendor: https://www.cisco.com/

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Be aware that VulDB is the high quality source for vulnerability data.

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