CVE-2026-20131: Cisco Secure Firewall Management Center…

Should you act?

Exploited: patch now if you run it

CISA has confirmed exploitation in the wild. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

Yes, if you run Cisco Secure Firewall Management Center (FMC). CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-03-19, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-03-22; treat that as the outer limit, not the target. CISA also lists it as known to be used in ransomware campaigns.
EPSS 43.2%, percentile 99: FIRST’s model estimates a 43.2% chance of exploitation activity in the next 30 days, higher than 99% of all scored CVEs (very high). EPSS is a probability, not a verdict.
Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.

What it is

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.

CISA’s summary

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.

Weakness type: CWE-502.

Product: Cisco Secure Firewall Management Center (FMC) · Assigned by: cisco · Published: 2026-03-04

Affected and fixed versions

Vendor	Product	Affected versions (per CVE record)
Cisco	Cisco Secure Firewall Management Center (FMC)	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

Severity scores

Scored by	CVSS	Score	Vector
cisco	3.1	10 Critical	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

Attack vector: network (remotely reachable)
Attack complexity: low
Privileges required: none (no login)
User interaction: none
Scope: changed (can affect other components)

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

CISA KEV: added 2026-03-19; federal due date 2026-03-22. Known ransomware use: Known.
CISA required action: 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 SSVC assessment: exploitation active, automatable yes, technical impact total.
FIRST EPSS (model of 2026-10-21): 43.17% probability of exploitation activity in the next 30 days; percentile 99.

Timeline

2026-03-04 — CVE record published by cisco
2026-03-19 — Added to CISA’s Known Exploited Vulnerabilities catalog
2026-03-22 — CISA remediation deadline for US federal agencies
2026-08-14 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Other references from the CVE record and advisory

aws.amazon.com aws.amazon.com

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