CVE-2026-20340
Cisco Secure Firewall Management Center Software Deserialization Arbitrary Root Command Execution Vulnerability
Published Sep 16, 2026
CVSS 3.1 · 8.8 High
EPSS < 1%
KEV · Not listed
Description
A vulnerability in Cisco Secure FMC Software could allow an authenticated, remote attacker to execute arbitrary commands at the root privilege level.
This vulnerability is due to unsecured deserialization of web-management user-controlled data. An attacker could exploit this vulnerability by authenticating to the device and sending a crafted HTTP payload. A successful exploit could allow the attacker to save the crafted payload and then execute it on the underlying operating system as root.
To exploit this vulnerability, the attacker must have valid credentials for a user account with at least the role of Security Analyst (read-only).
This vulnerability is due to unsecured deserialization of web-management user-controlled data. An attacker could exploit this vulnerability by authenticating to the device and sending a crafted HTTP payload. A successful exploit could allow the attacker to save the crafted payload and then execute it on the underlying operating system as root.
To exploit this vulnerability, the attacker must have valid credentials for a user account with at least the role of Security Analyst (read-only).
Affected Products
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CVE record
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NVD configurations
No data
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Red Hat packages
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OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| Cisco | Cisco Secure Firewall Management Center (FMC) | unknown |
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No data.
No data.
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| Cisco | Secure Firewall Management Center |
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Remediation
Tracking
Advisories
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity Low
Privileges Required Low
Scope Unchanged
Confidentiality Impact High
Integrity Impact High
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.745% probability within 30 days)
Exploitation none
Automatable no
Technical Impact total
References
History
Sep 19, 2026 11:00 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Cisco
Cisco secure Firewall Management Center |
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| Vendors & Products |
Cisco
Cisco secure Firewall Management Center |
Sep 17, 2026 5:30 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Sep 16, 2026 8:30 PM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A vulnerability in Cisco Secure FMC Software could allow an authenticated, remote attacker to execute arbitrary commands at the root privilege level. This vulnerability is due to unsecured deserialization of web-management user-controlled data. An attacker could exploit this vulnerability by authenticating to the device and sending a crafted HTTP payload. A successful exploit could allow the attacker to save the crafted payload and then execute it on the underlying operating system as root. To exploit this vulnerability, the attacker must have valid credentials for a user account with at least the role of Security Analyst (read-only). | |
| Title | Cisco Secure Firewall Management Center Software Deserialization Arbitrary Root Command Execution Vulnerability | |
| Weaknesses | CWE-502 | |
| References |
| |
| Metrics |
cvssV3_1
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Subscriptions
Weaknesses
