Security readout for executives and security teams
Plain-English summary
Certain Cisco Small Business switch software can be forced to reboot by malicious IPv6 traffic. The business impact is availability: affected switches may unexpectedly restart, disrupting network connectivity. The source bundle does not identify active exploitation or fixed versions, so remediation should be driven by Cisco’s advisory for the exact model and software release.
Executive priority
Prioritize this for networks where affected Cisco switches carry business-critical traffic or IPv6 is enabled. The issue is availability-focused rather than data theft, but an unexpected switch reboot can still interrupt operations. Resolve through vendor-confirmed upgrades or exposure reduction.
Technical view
CVE-2020-3363 is an unauthenticated remote denial-of-service flaw in Cisco Small Business Smart and Managed Switch IPv6 packet processing. Insufficient validation of incoming IPv6 traffic can allow a crafted IPv6 packet passing through an affected device to trigger an unexpected reboot. IPv4 traffic is not affected. CVSS v3.0 score is 8.6 high.
Likely exposure
Exposure is most relevant where Cisco Small Business 250 Series Smart Switches process IPv6 traffic, especially across untrusted or broadly reachable network segments. Organizations without IPv6 enabled or without affected Cisco Small Business switch models are less likely to be exposed, but should verify inventory and software versions.
Exploitation context
The bundle states remote unauthenticated exploitation is possible, with low attack complexity and availability impact. It does not include exploit code, observed exploitation, or CISA KEV listing; KEV is marked false. Treat this as a credible disruption risk, not confirmed active exploitation.
Researcher notes
The provided record names CWE-20 and describes insufficient IPv6 input validation causing reboot. Affected version data is incomplete in the bundle, and no patch version is quoted. Do not broaden affected products beyond the Cisco Small Business 250 Series entry without checking Cisco’s advisory.
Mitigation direction
- Check Cisco’s advisory for affected models, fixed releases, and supported upgrade paths.
- Upgrade affected Cisco Small Business switch software when a vendor-fixed release is available.
- Limit untrusted IPv6 traffic through affected switches where operationally feasible.
- Segment management and high-value network paths from untrusted IPv6 sources.
- Monitor affected switches for unexpected reboots and availability incidents.
Validation and detection
- Inventory Cisco Small Business 250 Series Smart Switches and record software versions.
- Confirm whether affected switches process IPv6 traffic in production paths.
- Compare exact models and software releases against Cisco’s advisory.
- Review availability monitoring for unexplained switch reboots or brief outages.
- Document compensating controls if immediate upgrade is not possible.
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-20: 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-2020-3363 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
- 20200805 Cisco Small Business Smart and Managed Switches 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.