Security readout for executives and security teams
Plain-English summary
Cisco Firepower Threat Defense devices using Inline Pair or Passive mode can be forced into a denial-of-service condition by a nearby unauthenticated attacker. The impact is availability: the device may reload, fail to boot correctly, or become inaccessible to administrators if the /ngfw partition fills.
Executive priority
Treat this as high priority for perimeter or segmentation firewalls in inline paths. The main business risk is loss of inspection or enforcement during a DoS, with possible manual recovery if storage fills. Urgency depends on whether affected interface modes are deployed.
Technical view
CVE-2020-3577 is an ingress packet-processing validation flaw in Cisco FTD Software for Inline Pair or Passive mode interfaces. Malformed Ethernet frame handling can trigger either /ngfw partition exhaustion requiring manual recovery, or a process crash that reloads the device. CVSS v3.0 is 7.4, with adjacent-network attack vector and high availability impact.
Likely exposure
Exposure is limited to Cisco Firepower Threat Defense deployments with interfaces configured as Inline Pair or Passive mode. The attacker must be adjacent, not necessarily internet-routed. The source bundle does not provide affected version ranges, so teams need vendor guidance and asset configuration review.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation evidence. The vulnerability is unauthenticated and low complexity, but requires adjacent network position and traffic through the affected device. No public exploit status is established in the supplied bundle.
Researcher notes
The bundle establishes vulnerability class, attack vector, mode-specific exposure, and impact, but does not include fixed version data. Avoid assuming broader Cisco product exposure. Validation should focus on FTD interface mode, release mapping from Cisco, and operational symptoms of reload or /ngfw exhaustion.
Mitigation direction
- Review Cisco’s advisory for affected releases and fixed software guidance.
- Prioritize FTD devices with Inline Pair or Passive mode interfaces.
- Plan remediation during a maintenance window because security devices may reload.
- Contact Cisco TAC if /ngfw fills or the device cannot boot.
- Monitor affected devices for unexpected reloads and partition exhaustion.
Validation and detection
- Inventory Cisco FTD appliances and virtual deployments.
- Identify interfaces configured as Inline Pair or Passive mode.
- Compare installed FTD versions with Cisco’s advisory guidance.
- Check device health for /ngfw partition usage anomalies.
- Review operational history for unexplained reloads or process crashes.
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
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CWE-20: Exact CWE lookup
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Open ATT&CK lookupCVE-2020-3577 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
- High
- CVSS
- 7.4 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
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:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H2.84Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.4HighVector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20201021 Cisco Firepower Threat Defense Software Inline Pair/Passive Mode 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 Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.