Security readout for executives and security teams
Plain-English summary
CVE-2020-3189 can let a remote unauthenticated attacker drain memory on Cisco Firepower Threat Defense devices through VPN logging behavior. Over time, this can cause instability or a full denial of service, affecting VPN and firewall availability.
Executive priority
High priority for organizations relying on Cisco FTD VPN or firewall availability. The issue affects availability rather than data theft, but a crash on exposed security infrastructure can disrupt remote access and network protection.
Technical view
Cisco FTD VPN System Logging fails to free memory for events generated when VPN sessions are created or deleted. Repeated VPN session lifecycle activity can leak small amounts of memory until system memory is depleted, causing unexpected behavior or device crashes. VPN System Logging is enabled by default.
Likely exposure
Exposure is most likely on Cisco Firepower Threat Defense deployments that provide VPN connectivity to untrusted or internet-reachable users. The source bundle does not include affected version ranges, so teams must confirm exact exposure against Cisco's advisory and local asset inventory.
Exploitation context
The CVSS vector indicates remote, unauthenticated, low-complexity exploitation with high availability impact. The bundle does not indicate CISA KEV listing or active exploitation. Treat exploitation as plausible for exposed VPN services, but not confirmed as observed in the wild from these sources.
Researcher notes
Key gaps are affected version detail and named fixed releases, which are not present in the provided bundle. The root issue maps to CWE-400 resource consumption and has CVSS 8.6 because it is network reachable, unauthenticated, and availability-impacting.
Mitigation direction
- Check Cisco's advisory for affected and fixed FTD release guidance.
- Prioritize review of internet-facing FTD VPN gateways.
- Plan a Cisco-supported upgrade if the device is in an affected release.
- Monitor FTD memory pressure, instability, and crash events.
- Restrict VPN exposure where operationally feasible and Cisco-supported.
Validation and detection
- Inventory Cisco FTD devices that provide VPN service.
- Confirm software versions against Cisco's advisory.
- Review whether VPN System Logging is enabled or defaulted.
- Check monitoring for gradual memory growth or recent FTD crashes.
- Validate upgrade status after applying Cisco-recommended fixes.
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-400: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-3189 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
- 8.6 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/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:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H3.94Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.6HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200506 Cisco Firepower Threat Defense Software VPN System Logging 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.
Uncontrolled Resource Consumption
Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.