Skip to content
Fencer Intel
critical 10.0

CVE-2026-20131 kev+ ransomware in the critical feed json

Cisco Secure Firewall Management Center Software Remote Code Execution Vulnerability

published 8mo ago modified 2mo ago also EUVD-2026-9444

cvss
10.0
version 3.1, CNA
cisa kev
Exploited
added 2026-03-19, used in ransomware
epss
44.4%
EPSS 44.4% chance of exploitation in 30 days, percentile 98%
public exploits
0
none known

Summary

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.

Patch / fix

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.

Is CVE-2026-20131 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Timeline

  1. CISA SSVC: exploitation active
  2. Published
  3. Added to CISA KEV
  4. CISA patch deadline

Known exploited

Added
7mo ago
Patch by
2026-03-22 (7mo ago)
Ransomware
Known to be used in ransomware campaigns
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.
Vendor, product
Cisco, Secure Firewall Management Center (FMC)
CISA name
Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data Vulnerability

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
8mo ago

Exploit prediction

44.43% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 10.0 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Affected products

  • Cisco Cisco Secure Firewall Management Center (FMC)

Classification

Weakness
  • CWE-502 Deserialization of Untrusted Data

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.