CVE-2021-1271: Cisco Web Security Appliance Stored Cross-Site Scripting Vulnerability

Severity: medium (CVSS 4.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-01-20 · updated 2026-06-17
Weakness: CWE-79

Description

A vulnerability in the web-based management interface of Cisco AsyncOS for Cisco Web Security Appliance (WSA) could allow an authenticated, remote attacker to conduct a stored cross-site scripting (XSS) attack against a user of the interface of an affected device. The vulnerability exists because the web-based management interface does not properly validate user-supplied input. An attacker could exploit this vulnerability by inserting malicious data into a specific data field in an affected interface. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface.

Affected products

Cisco Web Security Virtual Appliance: before 12.5.1 — fixed in 12.5.1

How to fix

Upgrade to a fixed version: Cisco Web Security Virtual Appliance 12.5.1. Check the vendor advisory for mitigations.

References

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