Interlock Ransomware Exploits Cisco FMC Zero-Day CVE-2026-20131 for Root Access

The Hacker News

March 18, 2026 at 4:00 PM

Actively Exploited

Ransomware CVE Zero-day Cisco Vulnerability Critical Amazon

Overview

Amazon Threat Intelligence has issued a warning regarding an active ransomware campaign known as Interlock, which is exploiting a significant vulnerability in Cisco's Secure Firewall Management Center (FMC) Software. This vulnerability, identified as CVE-2026-20131, has a maximum severity score of 10.0 and stems from an insecure deserialization of user-supplied Java byte streams. This flaw could allow attackers to gain root access without authentication, posing a serious risk to organizations using affected Cisco products. The exploitation of this vulnerability is concerning as it enables unauthorized access, potentially leading to data breaches and system compromises. Companies using Cisco FMC Software must take immediate action to protect their systems from this ongoing threat.

Key Takeaways

Active Exploitation: This vulnerability is being actively exploited by attackers. Immediate action is recommended.
Affected Systems: Cisco Secure Firewall Management Center (FMC) Software
Action Required: Organizations should immediately update their Cisco FMC Software to the latest version to mitigate this vulnerability.
Timeline: Newly disclosed

Original Article Summary

Amazon Threat Intelligence is warning of an active Interlock ransomware campaign that's exploiting a recently disclosed critical security flaw in Cisco Secure Firewall Management Center (FMC) Software. The vulnerability in question is CVE-2026-20131 (CVSS score: 10.0), a case of insecure deserialization of user-supplied Java byte stream, which could allow an unauthenticated, remote attacker to

Impact

Cisco Secure Firewall Management Center (FMC) Software

Exploitation Status

This vulnerability is confirmed to be actively exploited by attackers in real-world attacks. Organizations should prioritize patching or implementing workarounds immediately.

Timeline

Newly disclosed

Remediation

Organizations should immediately update their Cisco FMC Software to the latest version to mitigate this vulnerability. Additionally, they should review their security configurations and consider implementing network segmentation and access controls to limit exposure.

Additional Information

This threat intelligence is aggregated from trusted cybersecurity sources. For the most up-to-date information, technical details, and official vendor guidance, please refer to the original article linked below.

Related Topics: This incident relates to Ransomware, CVE, Zero-day, and 4 more.

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