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CVE-2021-1239: Cisco Firepower Management Center Stored Cross-Site Scripting Vulnerabilities

• Severity: medium (CVSS 4.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-01-13 · updated 2026-06-17
• Weakness: CWE-79

Description

Multiple vulnerabilities in the web-based management interface of Cisco Firepower Management Center (FMC) could allow an authenticated, remote attacker to conduct a stored cross-site scripting (XSS) attack against a user of the interface of an affected system. The vulnerabilities exist because the web-based management interface does not properly validate user-supplied input. An attacker could exploit these vulnerabilities by persuading a user of the interface to click a crafted link. A successful exploit could allow the attacker to execute arbitrary script code in the context of the affected interface or access sensitive, browser-based information.

Affected products

• Cisco Firepower Management Center: before 6.7.0 — fixed in 6.7.0

How to fix

Upgrade to a fixed version: Cisco Firepower Management Center 6.7.0. Check the vendor advisory for mitigations.

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-stored-xss-djKfCzf2
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-stored-xss-djKfCzf2

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