CVE-2026-20131
Cisco — Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability
Cisco · CWE-502 — Deserialization of untrusted data · in CISA KEV since 2026-03-19
EVRS 85 of 100 Immediate
Out-of-Band / Urgent Remediation
Rank 427 of 2,960 tracked
Raised to the floor for a confirmed exploited vulnerability.
Why it scores 85
Evidence available: 6 of 7 signalsListed in the CISA KEV catalog, and associated with known ransomware campaigns.
- CISA KEVApplied
- RansomwareApplied
- Vendor exploitationDid not apply
- EPSSApplied
- Microsoft Exploitability IndexNot applicable
- Pre-patch disclosureNo data
- KEV recencyDid not apply
- CVSSApplied
The band answers “how soon”, not “how bad”. No data for: Pre-patch disclosure. Why some signals show no data
Fix
Patch or fixed version identifiedCISA required action
Fixed in
Cisco Secure Firewall Management Center (FMC) Appliances -> 7.0
Affected versions
- secure firewall management center
6.4.0.136.4.0.146.4.0.156.4.0.166.4.0.176.4.0.187.0.07.0.0.17.0.17.0.1.17.0.27.0.2.17.0.37.0.47.0.57.0.67.0.6.17.0.6.27.0.6.37.0.77.0.87.0.8.17.1.07.1.0.17.1.0.27.1.0.37.2.07.2.0.17.2.17.2.27.2.37.2.3.17.2.47.2.4.17.2.57.2.5.17.2.5.27.2.67.2.77.2.87.2.8.17.2.97.2.107.2.10.17.2.10.27.3.07.3.17.3.1.17.3.1.27.4.07.4.17.4.1.17.4.27.4.2.17.4.2.27.4.2.37.4.2.47.4.37.4.47.4.57.6.07.6.17.6.27.6.2.17.6.37.6.47.7.07.7.107.7.10.17.7.1110.0.0
Remediation
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Fixed versions from NVD.
Evidence
Each value with its source| Measure | Value | Source |
|---|---|---|
| CVSS base scoreHow severe the flaw is in itself. It does not say how likely an attack is. | 10.0 | NVD |
| FIRST EPSSFIRST's estimate of the chance this is exploited in the next 30 days, and how that ranks against all CVEs. | 0.432 (98.7th pctl) | FIRST EPSS |
| Actively exploitedWhether a source of record has confirmed attacks using it in the wild. | Confirmed | CISA KEV |
| Ransomware campaign useWhether CISA has seen ransomware operators use it. | Known | CISA KEV |
| CISA remediation deadlineThe date US federal agencies must have fixed or mitigated it. | 2026-03-22 · CISA federal deadline · Overdue by 7 months | CISA KEV |
| Public exploit moduleA module existing is not the same as active exploitation. | None known | Metasploit |
| EUVD cross-referenceENISA's record: CVSS 10.0 (v3.1), assigned by cisco. | Listed | ENISA EUVD |
Description
NVDA vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device. This vulnerability is due to insecure deserialization of a user-supplied Java byte stream. An attacker could exploit this vulnerability by sending a crafted serialized Java object to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary code on the device and elevate privileges to root. Note: If the FMC management interface does not have public internet access, the attack surface that is associated with this vulnerability is reduced.
What CISA says to do