CVE-2026-20131: Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 19 Mar 2026, 15 days after the CVE record was published.
- How likely is exploitation in the next 30 days?
- 43.2%
EPSS score, percentile 98.7 of all scored records
- How severe?
- 10.0 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
Required action (CISA), due 22 Mar 2026: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected: 7.0.0; 7.0.0.1; 7.0.1; 7.1.0; 6.4.0.13; 7.0.1.1; 6.4.0.14; 7.1.0.1; 7.0.2; 6.4.0.15; 7.2.0; 7.0.2.1
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
CISA due date for this action: 22 March 2026.
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
Linked from CISA's catalog entry
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-rce-NKhnULJh
- https://nvd.nist.gov/vuln/detail/CVE-2026-20131
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | 7.0.0 |
| Affected | 7.0.0.1 |
| Affected | 7.0.1 |
| Affected | 7.1.0 |
| Affected | 6.4.0.13 |
| Affected | 7.0.1.1 |
| Affected | 6.4.0.14 |
| Affected | 7.1.0.1 |
| Affected | 7.0.2 |
| Affected | 6.4.0.15 |
| Affected | 7.2.0 |
| Affected | 7.0.2.1 |
Versions not listed are: unknown.
And 58 more version entries in the CVE record.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management contain a deserialization of untrusted data vulnerability in the web-based management interface that could allow an unauthenticated, remote attacker to execute arbitrary Java code as root on an affected device.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2026-20131 to its Known Exploited Vulnerabilities (KEV) catalog on 19 Mar 2026.
- CISA marks it as known to be used in ransomware campaigns.
- The due date CISA sets for the required action is 22 Mar 2026.
- The CVE record was published on 4 Mar 2026, 15 days before it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 10.0 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 43.2% (percentile 98.7), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact total.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability
A 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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 4 Mar 2026 | CVE record published |
| 19 Mar 2026 | Added to CISA KEV |
| 22 Mar 2026 | CISA due date for the required action |
| 14 Aug 2026 | CVE record last updated |
References
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