How severe is CVE-2026-20131?

CVE-2026-20131 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-20131 being actively exploited?

Yes. CVE-2026-20131 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-03-19, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2026-20131?

CVE-2026-20131 primarily affects Cisco Secure Firewall Management Center. In total, 71 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-20131?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2026-20131 have an EU (EUVD) identifier?

Yes. CVE-2026-20131 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9444. It is also flagged as exploited in the EUVD (since 2026-03-19).

When was CVE-2026-20131 published?

CVE-2026-20131 was published on 2026-03-04 and last updated on 2026-06-17.

CVE-2026-20131

CVE-2026-20131 is a critical-severity vulnerability in Cisco Secure Firewall Management Center with a CVSS 3.x base score of 10.0. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2026-03-19). The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
EPSS exploit prediction: 28% (98th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2026-03-19)
EU (EUVD) id: EUVD-2026-9444
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2026-03-19)
Weakness: CWE-502
Affected product: Cisco Secure Firewall Management Center
Published: 2026-03-04
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-20131?: 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.
How severe is CVE-2026-20131?: CVE-2026-20131 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-20131 being actively exploited?: Yes. CVE-2026-20131 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2026-03-19, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2026-20131?: CVE-2026-20131 primarily affects Cisco Secure Firewall Management Center. In total, 71 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-20131?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2026-20131 have an EU (EUVD) identifier?: Yes. CVE-2026-20131 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9444. It is also flagged as exploited in the EUVD (since 2026-03-19).
When was CVE-2026-20131 published?: CVE-2026-20131 was published on 2026-03-04 and last updated on 2026-06-17.

References

Affected products (71)

cpe:2.3:a:cisco:secure_firewall_management_center:6.4.0.13:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:6.4.0.14:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:6.4.0.15:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:6.4.0.16:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:6.4.0.17:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:6.4.0.18:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.0.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.1.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.2:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.2.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.4:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.5:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.6:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.6.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.6.2:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.6.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.7:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.8:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.0.8.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.1.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.1.0.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.1.0.2:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.1.0.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.0:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.0.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.2:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.3:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.3.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.4:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.4.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.5:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.5.1:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.5.2:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.6:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.7:*:*:*:*:*:*:*
cpe:2.3:a:cisco:secure_firewall_management_center:7.2.8:*:*:*:*:*:*:*

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