Security readout for executives and security teams
Plain-English summary
CVE-2020-3255 can let a remote unauthenticated attacker overwhelm Cisco Firepower Threat Defense devices. The impact is availability: traffic passing through the device can be denied, and the management interface can become sluggish. The condition depends on high-rate IPv4 or IPv6 traffic matching a configured block action.
Executive priority
Treat this as a high-priority availability risk for environments using Cisco FTD inline. It is not a data-theft issue based on the cited CVSS, but a firewall outage can disrupt business services and incident response visibility.
Technical view
Cisco describes inefficient memory management in FTD packet processing. A high packet rate through an affected device, when matching an access-control policy block action, can exhaust memory and cause denial of service for transit traffic. CVSS 3.0 is 7.5, with network attack vector and high availability impact only.
Likely exposure
Exposure is most likely where Cisco Firepower Threat Defense Software is deployed inline and processes untrusted or high-volume IPv4 or IPv6 traffic. The source bundle does not provide affected version ranges, so product inventory must be checked against Cisco guidance.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The described attack is unauthenticated and remote, but requires sustained high-rate traffic that matches a configured block action in an access control policy.
Researcher notes
This is CWE-400 resource consumption. The required traffic condition is important: packets must transit the device and match a configured block action. Sources do not provide affected version ranges, exploit proof, or specific fixed releases in the bundle.
Mitigation direction
- Check Cisco’s advisory for affected releases and vendor-supported remediation guidance.
- Inventory Cisco Firepower Threat Defense deployments and software versions.
- Prioritize remediation for inline perimeter or high-traffic inspection points.
- Monitor for memory exhaustion, transit traffic loss, and sluggish management access.
- Review operational capacity for absorbing abnormal high-rate traffic.
Validation and detection
- Confirm whether deployed products are Cisco Firepower Threat Defense Software.
- Compare deployed software versions against the Cisco advisory.
- Identify access control policies with configured block actions.
- Review device telemetry for memory pressure during traffic spikes.
- Check incident records for transient transit DoS with management sluggishness.
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-2020-3255 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
- 7.5 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/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:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
7.5HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200506 Cisco Firepower Threat Defense Software Packet Flood 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.