# CVE-2026-76420: Cisco Secure FMC AJP connector peer impersonation

Source: https://junglewise.ai/threats/cve-2026-76420-cisco-secure-fmc-ajp-connector-peer-impersonation  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-16. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-76420 · Severity: critical · CVSS 9 · Published 2026-09-16

Cisco Secure Firewall Management Center (FMC) is a centralized management platform for Cisco Secure Firewall products. A vulnerability in its Apache JServ Protocol (AJP) connector allows an unauthenticated attacker to impersonate a peer device and gain root-level command execution and full control of the FMC's REST APIs, effectively taking over the management platform. This can only be exploited when the backup tunnel connection to Cisco Secure Firewall Threat Defense (FTD) devices is unavailable.

Technologies: [Cisco Secure Firewall Management Center](https://junglewise.ai/threats/technologies/secure-firewall-management-center). Vendors: [Cisco](https://junglewise.ai/threats/vendors/cisco).

## Quick answers

**Is CVE-2026-76420 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-76420 being exploited in the wild.

**How severe is CVE-2026-76420?** Critical severity, with a CVSS score of 9, published 16 September 2026.

**Which products and versions are affected?** Cisco Secure Firewall Management Center.

**Is there a fix for CVE-2026-76420?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-76420 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-76420?** Check whether you run Cisco Secure Firewall Management Center. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

This vulnerability stems from incorrect initialization of encryption parameters for the AJP connector at boot time in Cisco Secure FMC Software. An unauthenticated, remote attacker can exploit this by sending crafted packets to the AJP connector, allowing peer device impersonation. Successful exploitation grants the attacker root command execution and full control over FMC REST APIs. Notably, this vulnerability requires the sftunnel connection between Cisco Secure FMC and Cisco Secure FTD to be down, reducing the attack window in properly configured deployments. Cisco has released software updates to address this vulnerability, with no workarounds available.

## Affected products

- Cisco Secure Firewall Management Center

## Timeline

- 2026-09-16: disclosed

## References

- [https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc2-multivulns-HXgcqRG](https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc2-multivulns-HXgcqRG)

## Related threats

- [Cisco Secure FMC SSO token forgery in ASDM handler](https://junglewise.ai/threats/cve-2026-76413-cisco-secure-fmc-sso-token-forgery-in-asdm-handler)
- [Cisco Secure FMC privilege escalation in remote diagnostics debugger](https://junglewise.ai/threats/cve-2026-76412-cisco-secure-fmc-privilege-escalation-in-remote-diagnostics)
- [Cisco Secure Firewall software resource lifecycle vulnerability](https://junglewise.ai/threats/cve-2026-20336-cisco-secure-firewall-software-resource-lifecycle-vulnerability)
- [Cisco Secure FMC and FTD sftunnel authentication bypass](https://junglewise.ai/threats/cve-2026-20323-cisco-secure-fmc-and-ftd-sftunnel-authentication-bypass)
- [Cisco Secure FMC and FTD memory exhaustion in sftunnel](https://junglewise.ai/threats/cve-2026-20295-cisco-secure-fmc-and-ftd-memory-exhaustion-in-sftunnel)