Unauthenticated RCE to root on widely deployed Cisco FMC; could disrupt security operations.
CVE-2026-20131
Unauthenticated RCE to root via FMC web UI; insecure Java deserialization.
Is CVE-2026-20131 being exploited?
Yes. CVE-2026-20131 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2026-20131?
CVE-2026-20131 is rated Critical with a CVSS score of 10.0. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-20131?
Yes. A fix has been recorded for CVE-2026-20131. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-20131 affect?
CVE-2026-20131 affects Cisco Secure Firewall Management Center (FMC) web interface, Cisco FMC appliances. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-20131?
Patch when released; restrict FMC external access.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote attacker can execute arbitrary Java code as root on FMC via crafted serialized object, enabling full control.
Patch when possible
- affected7.0.0
- affected7.0.0.1
- affected7.0.1
- affected7.1.0
- affected6.4.0.13
- affected7.0.1.1
- affected6.4.0.14
- affected7.1.0.1
- affected7.0.2
- affected6.4.0.15
- affected7.2.0
- affected7.0.2.1
- affected7.0.3
- affected7.1.0.2
- affected7.2.0.1
- affected7.0.4
- affected7.2.1
- affected7.0.5
- affected6.4.0.16
- affected7.3.0
- affected7.2.2
- affected7.3.1
- affected7.2.3
- affected7.1.0.3
- affected7.2.3.1
- affected7.2.4
- affected7.0.6
- affected7.2.4.1
- affected7.2.5
- affected7.3.1.1
- affected7.4.0
- affected6.4.0.17
- affected7.0.6.1
- affected7.2.5.1
- affected7.4.1
- affected7.2.6
- affected7.4.1.1
- affected7.0.6.2
- affected6.4.0.18
- affected7.2.7
- affected7.2.5.2
- affected7.3.1.2
- affected7.2.8
- affected7.6.0
- affected7.4.2
- affected7.2.8.1
- affected7.0.6.3
- affected7.4.2.1
- affected7.2.9
- affected7.0.7
- affected7.7.0
- affected7.4.2.2
- affected7.2.10
- affected7.6.1
- affected7.4.2.3
- affected7.0.8
- affected7.6.2
- affected7.7.10
- affected7.2.10.1
- affected7.0.8.1
- affected7.6.2.1
- affected7.2.10.2
- affected7.7.10.1
- affected7.4.2.4
- affected7.4.3
- affected7.7.11
- affected7.6.4
- affected10.0.0
- affected7.4.4
- affected7.4.5
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.