Security readout for executives and security teams
Plain-English summary
A malformed SSL/TLS message passing through affected Cisco Firepower 2100 firewalls running FTD SSL/TLS inspection can force the device to reload. That creates a temporary denial of service for traffic protected by the firewall. The device is expected to recover after reloading, but the outage can still disrupt business operations.
Executive priority
Treat this as high priority for environments relying on Firepower 2100 SSL/TLS inspection for critical traffic. The impact is availability, not data theft, but firewall reloads can interrupt protected business services. Prioritize internet-facing and high-throughput inspection paths first.
Technical view
CVE-2020-3562 is an unauthenticated remote denial-of-service issue in Cisco FTD Software on Firepower 2100 Series firewalls. The flaw is improper input validation in fields of specific SSL/TLS messages during SSL/TLS inspection. Successful exploitation causes device reload and availability loss. CVSS is 8.6, with network attack vector and no privileges required.
Likely exposure
Exposure is most likely where Cisco Firepower 2100 Series devices run Cisco FTD Software with SSL/TLS inspection enabled and process traffic from untrusted networks. The source bundle does not provide exact affected versions, so version confirmation must come from Cisco guidance.
Exploitation context
The source states an unauthenticated remote attacker can trigger the issue by sending a malformed SSL/TLS message through an affected device. The bundle does not cite active exploitation, and KEV status is false. No exploit maturity evidence is provided.
Researcher notes
The public bundle identifies the vulnerable feature, impact, CVSS vector, and affected product family, but not exact software versions or fixed releases. Avoid assuming exploit status or remediation details beyond Cisco’s advisory. CWE-119 is listed, but the description centers on improper SSL/TLS message field validation.
Mitigation direction
- Review Cisco’s advisory for affected releases, fixed releases, and any interim mitigations.
- Inventory Firepower 2100 devices running Cisco FTD Software.
- Prioritize remediation where SSL/TLS inspection handles internet-facing or untrusted traffic.
- Monitor for unexpected firewall reloads and related availability incidents.
- Confirm failover or redundancy coverage for affected firewall paths.
Validation and detection
- Confirm whether each Firepower 2100 device runs Cisco FTD Software.
- Check whether SSL/TLS inspection is enabled on relevant traffic paths.
- Compare installed software versions against Cisco’s advisory.
- Review device history for unexpected reloads or DoS symptoms.
- Validate that remediation follows Cisco-published guidance.
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-119: 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-2020-3562 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
- 20201021 Cisco Firepower 2100 Series SSL/TLS Inspection 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 Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.