Cisco FXOS Software Buffer Overflow Vulnerability
A vulnerability in Cisco FXOS Software could allow an authenticated, local attacker with administrative credentials to cause a buffer overflow condition. The vulnerability is due to incorrect bounds checking of values that are parsed from a specific file. An attacker could exploit this vulnerability by supplying a crafted file that, when it is processed, may cause a stack-based buffer overflow. A successful exploit could allow the attacker to execute arbitrary code on the underlying operating system with root privileges. An attacker would need to have valid administrative credentials to exploit this vulnerability.
- Published
- Sep 3, 2020
- Updated
- Jun 16, 2026
- EPSS
- 0.4% · 30th percentile
- CWE
- CWE-119
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Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.7 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.4%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 6.7
- CNA · cisco
- 6.0
- 0.7 point gap
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| cisco | firepower extensible operating system | cpe:2.3:o:cisco:firepower_extensible_operating_system |
| cisco | firepower 4110 | cpe:2.3:h:cisco:firepower_4110 |
| cisco | firepower 4112 | cpe:2.3:h:cisco:firepower_4112 |
| cisco | firepower 4115 | cpe:2.3:h:cisco:firepower_4115 |
| cisco | firepower 4120 | cpe:2.3:h:cisco:firepower_4120 |
| cisco | firepower 4125 | cpe:2.3:h:cisco:firepower_4125 |
| cisco | firepower 4140 | cpe:2.3:h:cisco:firepower_4140 |
| cisco | firepower 4145 | cpe:2.3:h:cisco:firepower_4145 |
| cisco | firepower 4150 | cpe:2.3:h:cisco:firepower_4150 |
| cisco | firepower 9300 | cpe:2.3:h:cisco:firepower_9300 |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- cisco firepower extensible operating systemup to 2.3.1.58 inclusive
Versions reported by the vendor
Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.
Cisco Cisco Firepower Extensible Operating System (FXOS)
- n/aaffected
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2015-6435An unspecified CGI script in Cisco FX-OS before 1.1.2 on Firepower 9000 devices and Cisco Unified Computing System (UCS) Manager before 2.2(42Plan
- CVE-2020-3172Cisco FXOS and NX-OS Software Cisco Discovery Protocol Arbitrary Code Execution and Denial of Service Vulnerability36Monitor
- CVE-2017-12277A vulnerability in the Smart Licensing Manager service of the Cisco Firepower 4100 Series Next-Generation Firewall (NGFW) and Firepower 930036Monitor
- CVE-2020-3456Cisco FXOS Software Firepower Chassis Manager Cross-Site Request Forgery Vulnerability35Monitor
- CVE-2017-3883A vulnerability in the authentication, authorization, and accounting (AAA) implementation of Cisco Firepower Extensible Operating System (FX35Monitor
- CVE-2020-3517Cisco FXOS and NX-OS Software Cisco Fabric Services Denial of Service Vulnerability34Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-119 · Improper Restriction of Operations within the Bounds of a Memory BufferCVSS vector
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Buffer ManipulationCAPEC-123likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.