Skip to content

CVE-2026-20131

Deserialization of Untrusted Data: Is CVE-2026-20131 real, exploitable, or a false positive? Here's the community verdict.

signals

public sources

Exploited in wild
Yes
CISA KEV
Public exploit
None known
Metasploit/EDB/PoC
Base severity
10 Critical
CVSS
Exploitation prob.
28%
FIRST EPSS
Weakness
CWE-502 · Deserialization of Untrusted Data
CWE

Confirmed exploited in the wild. Patch this first, regardless of the base score.

baseline read

auto · not a community verdict

Real — exploited in the wild

CISA confirms active exploitation. Treat scanner hits as true positives unless your specific version or config is unaffected.

Based on CISA KEV

Confirm or dispute →

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

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.

Published

Embed this verdict
TruePositive verdict for CVE-2026-20131
Markdown
[![TruePositive verdict](https://www.truepositive.app/cve/CVE-2026-20131/badge.svg)](https://www.truepositive.app/cve/CVE-2026-20131)
HTML
<a href="https://www.truepositive.app/cve/CVE-2026-20131"><img src="https://www.truepositive.app/cve/CVE-2026-20131/badge.svg" alt="TruePositive verdict for CVE-2026-20131"></a>

Live badge that updates automatically as the community verdict changes.

Community ground truth

Be the first practitioner to weigh in

So far this is only TruePositive's editorial baseline from public sources. Add your real-world verdict below — it becomes the signal the next person triaging this relies on.

🥇 The first 50 practitioners to contribute earn a Founding Contributor badge.

In your experience, is this finding real and exploitable?

awaiting field verdicts
Real, but not a risk here
Not a real issue

Curated baseline: TruePositive's read from public sources is Real & exploitable — a starting point, not a community verdict.

No account needed. Anonymous verdicts post as an unverified signal. Log in to make yours verified and earn reputation.

Field notes & remediation

Verdicts are the quick signal. Notes are the evidence and fixes behind them.

  • 0
    Field note · TruePositive EditorialCurated

    Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data 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. Listed in the CISA KEV catalog (added 2026-03-19) — confirmed exploited in the wild, not theoretical. It is linked to known ransomware campaigns. FIRST EPSS puts the chance of exploitation in the next 30 days at ~28%. Treat it as real and prioritize remediation over triage.

  • 0
    Remediation · TruePositive EditorialCurated

    Required action for Cisco Secure Firewall Management Center (FMC): 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 set a federal remediation due date of 2026-03-22. After patching, verify the vulnerable path is no longer reachable before closing the finding.

Add a field note or remediationoptional
Note type

What are you adding?

Markdown supported · minimum 20 characters.

Same weakness: CWE-502 · Deserialization of Untrusted Data.