CVE-2026-20343 Cisco Secure FMC Software - Authentication Bypass

Cisco Secure FMC Software contains an information disclosure and denial of service vulnerability caused by lack of authentication in a critical API, letting unauthenticated remote attackers download sensitive files and exhaust disk space, exploit requires no authentication.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.45% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Information Disclosure, Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-306

Vendor fix

Update to the latest version with authentication enforced on the critical API.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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