How severe is CVE-2021-34761?

CVE-2021-34761 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-34761 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34761?

CVE-2021-34761 primarily affects Cisco Firepower Management Center Virtual Appliance. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34761?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-34761 published?

CVE-2021-34761 was published on 2021-10-27 and last updated on 2026-06-17.

CVE-2021-34761

CVE-2021-34761 is a medium-severity vulnerability in Cisco Firepower Management Center Virtual Appliance with a CVSS 3.x base score of 4.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-668.

Key facts

Severity: Medium (CVSS 3.x base score 4.4)
CVSS v2: 6.6
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-668
Affected product: Cisco Firepower Management Center Virtual Appliance
Published: 2021-10-27
Last modified: 2026-06-17

Description

A vulnerability in Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to overwrite or append arbitrary data to system files using root-level privileges. The attacker must have administrative credentials on the device. This vulnerability is due to incomplete validation of user input for a specific CLI command. An attacker could exploit this vulnerability by authenticating to the device with administrative privileges and issuing a CLI command with crafted user parameters. A successful exploit could allow the attacker to overwrite or append arbitrary data to system files using root-level privileges.

Frequently asked questions

What is CVE-2021-34761?: A vulnerability in Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to overwrite or append arbitrary data to system files using root-level privileges. The attacker must have administrative credentials on the device. This vulnerability is due to incomplete validation of user input for a specific CLI command. An attacker could exploit this vulnerability by authenticating to the device with administrative privileges and issuing a CLI command with crafted user parameters. A successful exploit could allow the attacker to overwrite or append arbitrary data to system files using root-level privileges.
How severe is CVE-2021-34761?: CVE-2021-34761 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over local access with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-34761 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-34761?: CVE-2021-34761 primarily affects Cisco Firepower Management Center Virtual Appliance. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-34761?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-34761 published?: CVE-2021-34761 was published on 2021-10-27 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-file-write-SHVcmQVc

Affected products (13)

cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.1.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sourcefire_defense_center:6.2.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sourcefire_defense_center:6.6.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:sourcefire_defense_center:7.1.0:*:*:*:*:*:*:*

More vulnerabilities in Cisco Firepower Management Center Virtual Appliance

CVE-2018-0365 — High (CVSS 8.8): A vulnerability in the web-based management interface of Cisco Firepower Management Center could allow an…
CVE-2021-34781 — High (CVSS 8.6): A vulnerability in the processing of SSH connections for multi-instance deployments of Cisco Firepower Threat Defense…
CVE-2021-34762 — High (CVSS 8.1): A vulnerability in the web-based management interface of Cisco Firepower Management Center (FMC) Software could allow…
CVE-2021-34756 — Medium (CVSS 6.7): Multiple vulnerabilities in the CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated,…
CVE-2021-34755 — Medium (CVSS 6.7): Multiple vulnerabilities in the CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated,…
CVE-2021-34764 — Medium (CVSS 4.8): Multiple vulnerabilities in the web-based management interface of Cisco Firepower Management Center (FMC) Software…

All CVEs affecting Cisco Firepower Management Center Virtual Appliance →

Other CWE-668 (Exposure of Resource to Wrong Sphere) vulnerabilities

CVE-2025-2857 — Critical (CVSS 10.0): Following the recent Chrome sandbox escape (CVE-2025-2783), various Firefox developers identified a similar pattern in…
CVE-2019-8779 — Critical (CVSS 10.0): A logic issue applied the incorrect restrictions. This issue was addressed by updating the logic to apply the correct…
CVE-2012-1846 — Critical (CVSS 10.0): Google Chrome 17.0.963.66 and earlier allows remote attackers to bypass the sandbox protection mechanism by leveraging…
CVE-2022-43684 — Critical (CVSS 9.9): ServiceNow has released patches and an upgrade that address an Access Control List (ACL) bypass issue in ServiceNow…
CVE-2022-24900 — Critical (CVSS 9.9): Piano LED Visualizer is software that allows LED lights to light up as a person plays a piano connected to a computer.…
CVE-2019-16541 — Critical (CVSS 9.9): Jenkins JIRA Plugin 3.0.10 and earlier does not declare the correct (folder) scope for per-folder Jira site…

Browse all CWE-668 (Exposure of Resource to Wrong Sphere) vulnerabilities →