Cisco FXOS Software for Firepower 4100/9300 Series Appliances Secure Boot Bypass Vulnerability
Priority LOW 36CWE-693Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-693.
Summary
A vulnerability in the secure boot process of Cisco FXOS Software could allow an authenticated, local attacker to bypass the secure boot mechanisms. The vulnerability is due to insufficient protections of the secure boot process. An attacker could exploit this vulnerability by injecting code into a specific file that is then referenced during the device boot process. A successful exploit could allow the attacker to break the chain of trust and inject code into the boot process of the device which would be executed at each boot and maintain persistence across reboots.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00348 28th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Cisco | Cisco Firepower Extensible Operating System (FXOS) | all versions | — | No fix listed | CNA |
- Cisco Firepower Extensible Operating System (FXOS) VendorCisco Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 17
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:cisco:firepower_extensible_operating_system:*:*:*:*:*:*:*:* | before 2.4.1.268; 2.6 to before 2.6.1.214; 2.7 to before 2.7.1.131 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:firepower_4110:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4112:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4115:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4120:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4125:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4140:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4145:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_4150:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-24:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
- cpe:2.3:o:cisco:firepower_extensible_operating_system:*:*:*:*:*:*:*:* Versions before 2.4.1.268; 2.6 to before 2.6.1.214; 2.7 to before 2.7.1.131 Vulnerable ·Cisco
- cpe:2.3:h:cisco:firepower_4110:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4112:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4115:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4120:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4125:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4140:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4145:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_4150:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-24:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Show 7 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:h:cisco:firepower_9300_sm-36:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-40:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-44:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-44_x_3:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-48:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-56:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:firepower_9300_sm-56_x_3:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
- cpe:2.3:h:cisco:firepower_9300_sm-36:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-40:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-44:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-44_x_3:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-48:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-56:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:firepower_9300_sm-56_x_3:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2020-3455
- 2026-10-03 Alias added: GHSA-4c77-wcw2-9gh7
References
More Cisco Firepower Extensible Operating System vulnerabilities
- TI-2018-00269 Resource management flaw in Cisco FXOS and NX-OS unknown CVSS 3.0CRITICAL 9.8
- TI-2015-05417 An unspecified CGI script in Cisco FX-OS before 1.1.2 on Firepower 9000 devices and Cisco… CVSS 3.0CRITICAL 9.8
- TI-2019-01480 Cisco FXOS and NX-OS Software Simple Network Management Protocol Denial of Service Vulnerability CVSS 3.1HIGH 8.6
- TI-2019-01225 Cisco FXOS and NX-OS Lightweight Directory Access Protocol Denial of Service Vulnerabilities CVSS 3.0HIGH 8.6
- TI-2019-01224 Cisco FXOS and NX-OS Lightweight Directory Access Protocol Denial of Service Vulnerabilities CVSS 3.0HIGH 8.6
- TI-2020-03063 Cisco FXOS and NX-OS Software Cisco Fabric Services Denial of Service Vulnerability CVSS 3.1HIGH 8.6
Sources
- CVE-2020-3455 · CVE Program
- CVE-2020-3455 · NVD
- FIRST EPSS
- GHSA-4c77-wcw2-9gh7 · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences