CVE-2026-20079
Auth Bypass in Cisco Secure Firewall Management Center 10.0.0 … 7.7.12
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-20079 is a critical-severity Authentication Bypass Using an Alternate Path or Channel (CWE-288) vulnerability in Cisco Secure Firewall Management Center. Its CVSS base score is 10.0 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to AC-25 (Reference Monitor) and AC-3 (Access Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A vulnerability in the web interface of Cisco Secure Firewall Management Center (FMC) Software stems from an improper system process created at boot time. The flaw, tracked as CVE-2026-20079 and assigned CWE-288, permits an unauthenticated remote attacker to bypass authentication controls and execute arbitrary script files, ultimately obtaining root access to the underlying operating system. It carries a maximum CVSS 3.1 score of 10.0 reflecting network attack vector, low complexity, and full impact across confidentiality, integrity, and availability in a changed scope.
An attacker can exploit the issue by sending crafted HTTP requests to an affected FMC device. Successful exploitation allows execution of a variety of scripts and commands that grant full root privileges on the host operating system without any prior authentication or user interaction.
The Cisco Security Advisory at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-onprem-fmc-authbypass-5JPp45V2 addresses the issue and is the primary source for mitigation guidance and patch availability.
EPSS for the CVE rose from a lower baseline to a peak of 0.2102 with a current value of 0.1114, indicating emerging exploitation interest after disclosure that warrants renewed attention from defenders.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9438
Vulnerability Data
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. …
more
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.
- CWE(s)
- KEV Date Added
- 09 September 2026
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 7 hardening rules · 3 OS baselines
V6.4.3V6.6.1V12.1.3
Mitigating Controls (NIST 800-53 r5) AI
Requires a tamperproof, always-invoked reference monitor that structurally blocks bypass via any alternate path.
Enforces authorization checks on every logical access path, eliminating unauthenticated alternate channels.
Mandates unique identification and authentication for all organizational users, covering the primary authentication requirement.
Controls all external and key internal interfaces, reducing the chance of unauthenticated alternate channels.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Requiring authentication on every channel and path directly eliminates alternate-path bypasses.
Enforcing authorizations and least privilege across all access vectors prevents unauthenticated alternate paths.
Protecting networks and environments from unauthorized logical access blocks bypass via undocumented channels.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect alternate-path bypasses but does not prevent them in production.
Secure authentication control directly mitigates bypass by requiring strong, consistent authentication on all paths.
Access control policy directly addresses alternate authentication paths by requiring all channels to enforce authentication.
Authentication information management ensures credentials and mechanisms are consistently applied across all access paths.
Access rights provisioning and review prevent bypass via unmonitored or alternate channels.
Privileged access rights control reduces risk of bypass through elevated or alternate paths.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248598 There must be no ".shosts" files on the OL 8 operating system. prevents CWE-288
- V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-288
Oracle Linux 9 (2 rules)
- V-271757 OL 9 file systems must not contain shosts.equiv files. prevents CWE-288
- V-271758 OL 9 file systems must not contain .shosts files. prevents CWE-288
RHEL 7 (3 rules)
- V-204440 Red Hat Enterprise Linux operating systems version 7.2 or newer using Unified Extensible Firmware Interface (UEFI) must require authentication upon booting into single-user and maintenance modes. prevents CWE-288
- V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-288
- V-204424 The Red Hat Enterprise Linux operating system must not allow accounts configured with blank or null passwords. prevents CWE-288