CVE-2026-20079: Cisco Firewall Management Center Authentication Bypass Using an Alternate Path or Channel Vulnerability

What it is

A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to bypass authentication and execute script files on an affected device to obtain root access to the underlying operating system.  This vulnerability is due to an improper system process that is created at boot time. An attacker could exploit this vulnerability by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute a variety of scripts and commands that allow root access to the device. 

Description quoted from the CVE record (assigned by cisco, published 2026-03-04).

Weakness: Authentication Bypass Using an Alternate Path or Channel

How it can be exploited

Exploitable over the network with low attack complexity needing no privileges and no user interaction. Impact: confidentiality high, integrity high, availability high. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CISA assessment (SSVC): CISA assesses exploitation as active. Automatable: yes. Technical impact: total.

On CISA KEV since

2026-09-09

US federal deadline

2026-09-12

Ransomware use

Not known

Public exploit evidence (Exploit Observer)

Also known as: BDU:2026-06300, EUVD-2026-9438, GHSA-mv8w-c2qv-cgrg

VEDAS cluster: VEDAS:AZTECAXOLOTL

Exploit Observer links 11 pieces of public exploit code or detection modules that name this CVE or one of its aliases.

Exploit code and modules (11)

Code that names this CVE. A repository can be a working exploit, a scanner, a fake or malware; read it before running anything.

• Nuclei template: https://raw.githubusercontent.com/projectdiscovery/nuclei-templates/main/http/cves/2026/CVE-2026-20079.yaml
• Code repository: https://github.com/0xblackash/cve-2026-20079
• Code repository: https://github.com/b1gchoi/cve-2026-20079
• Code repository: https://github.com/cyberauth/cve-2026-20079
• Code repository: https://github.com/diegoarias008/cve-2026-20079-checker
• Code repository: https://github.com/sushilsin/cve-2026-20079
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/nuclei/2026/CVE-2026-20079.yaml
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/nuclei/2026/CVE-2026-20079.yaml
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-20079.rules
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-20079.rules
• Code repository: https://raw.githubusercontent.com/ARPSyndicate/vedas-signatures/main/suricata/2026/CVE-2026-20079.rules

Research and write-ups (2)

• Research or write-up: https://banks.tools/writeups/cve-2026-20079-cisco-secure-fmc
• Research or write-up: https://horizon3.ai/attack-research/vulnerabilities/cve-2026-20079

Vulnerability databases and vendor advisories (4)

Catalogue entries, not exploit evidence.

• Vulnerability database or vendor advisory: https://euvd.enisa.europa.eu/enisa/EUVD-2026-9438
• Vulnerability database or vendor advisory: https://github.com/advisories/GHSA-mv8w-c2qv-cgrg
• Vulnerability database or vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-20079
• Vulnerability database or vendor advisory: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20079

News (3)

• News: https://www.bleepingcomputer.com/news/security/cisco-confirms-cve-2026-20079-secure-fmc-flaw-exploited-in-attacks
• News: https://www.helpnetsecurity.com/2026/09/10/cisco-fmc-exploited-cve-2026-20079-cve-2026-20316
• News: https://www.techgines.com/post/cve-2026-20079-cisco-fmc-auth-bypass-sandworm-qilin

87 more references returned by Exploit Observer did not name this CVE or an alias, so they are left out.

VEDAS data as of 2026-11-01T17:12 UTC; fetched 2026-11-02.

Live scores

EPSS

0.887
very likely to be attacked soon

VEDAS

0.985
strong exploit evidence

On CISA KEV

Yes, since 2026-09-09

Detection rule

Nuclei · Suricata

Thin horizontal line: the “likely” (EPSS 0.10) or “strong” (VEDAS 0.90) threshold. Shaded “no data” areas are periods when cve-scores did not publish. The vertical line is the day CISA added it to its exploited list.

VEDAS flagged this bug about 32 days before CISA confirmed attacks.

Who is affected

Version ranges exactly as the CVE record states them. “Before X” means X is the first fixed version.

Exploit Observer also maps it to: cisco secure_firewall_management_center.

How to fix it

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset’s internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Vendor guidance:

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-onprem-fmc-authbypass-5JPp45V2
• https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk
• https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk
• https://nvd.nist.gov/vuln/detail/CVE-2026-20079

How to detect it

Nuclei template (active check)

Cisco Secure Firewall Management Center - Authentication Bypass

A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated, remote attacker to bypass authentication and execute script files on an affected device to obtain root access to the underlying operating system.  This vulnerability is due to an improper system process that is created at boot time. An attacker could exploit this vulnerability by sending crafted HTTP requests to an affected device.

Name and description quoted from the template, written by VEDAS.

The template sends 2 requests (GET /help/about.cgi, GET /help/about.cgi); it decides using dsl matchers. Severity in the template: critical. Marked as not yet verified against a live vulnerable target.

Run it against a host you own or are authorised to test:

nuclei -u https://your-host -t CVE-2026-20079.yaml

id: CVE-2026-20079

info:
  name: "Cisco Secure Firewall Management Center - Authentication Bypass"
  author: vedas-arpsyndicate
  severity: critical
  description: |
    A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software could allow an
    unauthenticated, remote attacker to bypass authentication and execute script files on an affected device to
    obtain root access to the underlying operating system.  This vulnerability is due to an improper system
    process that is created at boot time. An attacker could exploit this vulnerability by sending crafted HTTP
    requests to an affected device.
  reference:
    - https://www.exploit.observer/?keyword=CVE-2026-20079&match=exact
    - https://subdomain.center/?engine=ammonites&keyword=cisco&match=exact
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 10
    cve-id: CVE-2026-20079
    cwe-id: CWE-288
  metadata:
    verified: false
  tags: cve,cve2026,cisco,fmc,auth-bypass,rce,unauth,kev,vkev
flow: http(1) && http(2)

http:
  - raw:
      - |
        GET /help/about.cgi HTTP/1.1
        Host: {{Hostname}}

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 302'
          - 'contains(body, "Invalid session ID")'
        condition: and
        internal: true

  - raw:
      - |
        GET /help/about.cgi HTTP/1.1
        Host: {{Hostname}}
        Cookie: CGISESSID=csm_processes

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'contains_all(body, "Cisco Secure Firewall Management Center", "Model", "OS", "Hostname")'
        condition: and

CVE-2026-20079.yaml on GitHub

Suricata rules (network detection)

1 rule that alert on traffic matching this exploit: VEDAS CVE-2026-20079 Cisco Secure Firewall Management Center - Authentication Bypass. Add them to your Suricata rule set and reload.

alert http $EXTERNAL_NET any -> $HTTP_SERVERS $HTTP_PORTS (msg:"VEDAS CVE-2026-20079 Cisco Secure Firewall Management Center - Authentication Bypass"; flow:established,to_server; http.uri; content:"/help/about.cgi"; nocase; fast_pattern; classtype:web-application-attack; reference:cve,CVE-2026-20079; reference:url,https://www.exploit.observer/?keyword=CVE-2026-20079&match=exact; reference:url,https://subdomain.center/?engine=ammonites&keyword=cisco&match=exact; sid:1010403; rev:1;)

CVE-2026-20079.rules on GitHub

References

Exploits and technical analysis

• https://blog.talosintelligence.com/fmc-ongoing-exploitation/ (third-party-advisory)

Government sources

• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20079 (government-resource)

Other references

• cisco-sa-onprem-fmc-authbypass-5JPp45V2
• http://seclists.org/fulldisclosure/2026/Aug/80

Other databases

• CVE record (cve.org)
• NVD
• Exploit Observer

Where this comes from

This advisory is generated automatically by VEDAS from: CVE.org record, CISA KEV, cve-scores (EPSS and VEDAS), Exploit Observer, vedas-signatures. Text in quotes is reproduced from the source; everything else is a fixed template filled with source fields. Nothing here is written by a language model. Check the vendor advisory before acting, and read how VEDAS and Exploit Observer work, and their limits.