CVE-2026-20056
Anti-Malware Bypass in Cisco AsyncOS DVS Engine
Publication date: 2026-02-04
Last updated on: 2026-02-04
Assigner: Cisco Systems, Inc.
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| cisco | asyncos | * |
| cisco | asyncos | 15.2.5-011 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| 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. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
[{'type': 'paragraph', 'content': 'CVE-2026-20056 is a medium-severity vulnerability in the Dynamic Vectoring and Streaming (DVS) Engine of Cisco AsyncOS Software for Cisco Secure Web Appliance. It occurs because the software improperly handles certain archive files.'}, {'type': 'paragraph', 'content': "An unauthenticated, remote attacker can exploit this by sending specially crafted archive files that should be blocked by the anti-malware scanner. This allows the attacker to bypass the scanner and download malicious archive files onto an end user's workstation."}, {'type': 'paragraph', 'content': 'However, the malware will not execute automatically; it requires the user to manually extract and launch the malicious content.'}] [1]
How can this vulnerability impact me? :
This vulnerability can impact you by allowing an attacker to bypass the anti-malware protections of the Cisco Secure Web Appliance and deliver malicious archive files to your workstation.
If a user extracts and launches the malicious files, malware could be installed on the workstation, potentially compromising the system.
There are no workarounds available, so the only way to mitigate this risk is to upgrade to the fixed software versions provided by Cisco.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, Cisco advises all users to upgrade to the fixed software versions. The first fixed release addressing this issue is AsyncOS 15.2.5-011.
Upgrades can be performed via the appliance’s web interface using the System Upgrade options.
There are no workarounds available for this vulnerability, so applying the fixed software is the only effective mitigation.