CVE-2022-20784: Cisco Web Security Appliance Filter Bypass Vulnerability

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.9% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2022-04-06 · updated 2026-06-17
Weakness: CWE-20

Description

A vulnerability in the Web-Based Reputation Score (WBRS) engine of Cisco AsyncOS Software for Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to bypass established web request policies and access blocked content on an affected device. This vulnerability is due to incorrect handling of certain character combinations inserted into a URL. An attacker could exploit this vulnerability by sending crafted URLs to be processed by an affected device. A successful exploit could allow the attacker to bypass the web proxy and access web content that has been blocked by policy.

Affected products

Cisco Web Security Appliance (WSA): from 11.7.0 before 14.0.2 — fixed in 14.0.2

How to fix

Upgrade to a fixed version: Cisco Web Security Appliance (WSA) 14.0.2. Check the vendor advisory for mitigations.

References

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