Security readout for executives and security teams
Plain-English summary
Cisco FMC has a remotely reachable denial-of-service flaw in a host input API daemon. An attacker who can reach the service may cause the daemon to restart, and repeated attempts could disrupt API availability. The source bundle does not identify specific affected versions or provide evidence of active exploitation.
Executive priority
Treat as a medium-priority availability issue. It does not indicate compromise of confidentiality or integrity, but disruption of FMC APIs can affect security operations. Prioritize exposed or business-critical FMC systems and confirm Cisco-supported remediation.
Technical view
CVE-2020-3557 is caused by improper certificate validation in Cisco Firepower Management Center Software's host input API daemon. Cisco describes unauthenticated remote exploitation through a crafted data stream that can restart the daemon. CVSS 3.1 is 5.3, with network attack vector, low complexity, no privileges, no user interaction, and low availability impact.
Likely exposure
Exposure is likely limited to organizations running Cisco Firepower Management Center where the host input daemon is reachable by an attacker. The provided sources do not list affected versions, CPEs, or deployment prerequisites, so version-specific exposure must be confirmed against Cisco guidance.
Exploitation context
The bundle does not show CISA KEV inclusion or cited evidence of active exploitation. The described impact is API denial of service through repeated daemon restarts, not data theft or code execution. Practical risk rises if FMC management services are reachable from untrusted networks.
Researcher notes
Key evidence gaps are affected version detail, fixed release detail, and any real-world exploitation signal. Analysis should stay anchored to Cisco's advisory and CVE data. Validate reachability and daemon restart symptoms defensively without attempting crafted-stream reproduction.
Mitigation direction
- Review Cisco's advisory for affected releases and fixed-release guidance.
- Update affected FMC deployments following Cisco's published remediation guidance.
- Prioritize systems where FMC services are reachable from untrusted networks.
- Monitor for repeated host input daemon restarts or API disruption.
Validation and detection
- Inventory Cisco Firepower Management Center deployments and installed software versions.
- Compare installed versions against Cisco's advisory for CVE-2020-3557.
- Review FMC logs for recurring host input daemon restarts.
- Confirm API availability remains stable after remediation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-295: Exact CWE lookup
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Open ATT&CK lookupCVE-2020-3557 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- 20201021 Cisco Firepower Management Center Software Denial of Service VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Certificate Validation
Improper Certificate Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.