CVE-2021-34764 | Cisco Firepower Management Center Software Cross-Site Scripting and Open Redirect Vulnerabilities

Multiple vulnerabilities in the web-based management interface of Cisco Firepower Management Center (FMC) Software could allow an attacker to execute a cross-site scripting (XSS) attack or an open redirect attack. For more information about these vulnerabilities, see the Details section of this advisory.

Published: 2021-10-27 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-34764 is rated Low Risk (34.8/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.59%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-34764

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.19% 0.59% +0.40%
2 2025-11-07 0.32% 0.19% -0.12%
3 2025-03-19 — 0.32% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-34764

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 1.7 2.7 [email protected]
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 2.7 [email protected]
5.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.6 4.9 [email protected]

Weakness enumeration for CVE-2021-34764

Affected software / configurations for CVE-2021-34764

Vendor Product Version Raw CPE
cisco firepower_management_center_virtual_appliance 6.1.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.1.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.2.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.2.3 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.3:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.3.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.4.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.5.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.6.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.6.1 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.1:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 6.7.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 7.0.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*
cisco firepower_management_center_virtual_appliance 7.1.0 cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.1.0:*:*:*:*:*:*:*
cisco firepower_threat_defense < 6.4.0.13 cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
cisco firepower_threat_defense >= 6.5.0, < 6.6.5 cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
cisco firepower_threat_defense >= 6.7.0, < 6.7.0.3 cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.1.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.1.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.2.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.2.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.2.3 cpe:2.3:a:cisco:sourcefire_defense_center:6.2.3:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.3.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.4.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.5.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.6.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.6.1 cpe:2.3:a:cisco:sourcefire_defense_center:6.6.1:*:*:*:*:*:*:*
cisco sourcefire_defense_center 6.7.0 cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 7.0.0 cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*
cisco sourcefire_defense_center 7.1.0 cpe:2.3:a:cisco:sourcefire_defense_center:7.1.0:*:*:*:*:*:*:*

References for CVE-2021-34764

cvelogic Threat Intelligence