CVE-2026-20343 Cisco Secure Firewall Management Center Software Information Disclosure and Disk Denial of Service Vulnerability
Unauthenticated remote attackers can download sensitive files and exhaust disk space on Cisco Secure Firewall Management Center devices, causing denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-20343?
CVE-2026-20343 is a high-severity missing authorization vulnerability in Cisco Secure Firewall Management Center (FMC), published on 16 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A vulnerability in a critical API for Cisco Secure FMC Software could allow an unauthenticated, remote attacker to download sensitive files and use unbounded disk space. This vulnerability exists because a critical API lacks authentication. An attacker could exploit this vulnerability by repeatedly invoking the API. A successful exploit could allow the attacker to download sensitive files that should be restricted and consume disk space so the device could become unresponsive, causing a DoS condition.
Weakness: CWE-306
Which versions are affected by CVE-2026-20343?
How do I fix CVE-2026-20343?
No fix has been published for CVE-2026-20343 yet. Limit exposure of the affected software until one is available.
Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.
Is CVE-2026-20343 being exploited?
There is no known exploitation of CVE-2026-20343 in the wild and no public exploit code.
Sources
Also known as GHSA-mxj5-v55g-6rm4.