SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2021-1239

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…

MEDIUM 4.8EPSS 0.62%

Does this matter?

Lower severity and a low EPSS score (0.62%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 3.1
4.8 MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
EPSS
0.62% probability · 50th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-79
Affected
cisco/secure firewall management center
Source
psirt@cisco.com
EPSS trend
0%3%5%26 October 2026: 0.62%26 October 202626 October 2026

EPSS 0.6% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.