Security readout for executives and security teams
Plain-English summary
CVE-2020-3500 can make an affected Cisco ASR 5000 Series device running StarOS reload when it receives specially crafted IPv6 traffic. The impact is service interruption, not data theft or system takeover. IPv4 traffic is not affected.
Executive priority
Treat as a targeted availability risk for telecom or carrier infrastructure using Cisco ASR 5000 with IPv6. Prioritize affected, externally reachable systems, but do not treat it as a confirmed active-exploitation emergency from the supplied evidence.
Technical view
The flaw is in Cisco StarOS IPv6 handling and is attributed to insufficient validation of incoming IPv6 traffic. It is remotely reachable without authentication, but the CVSS vector rates attack complexity as high. Successful exploitation causes device reload and denial of service only.
Likely exposure
Exposure is most relevant where Cisco ASR 5000 Series Software processes reachable IPv6 traffic. Organizations without affected Cisco ASR 5000/StarOS deployments, or without IPv6 paths to them, are unlikely to be exposed based on the supplied sources.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The described outcome is denial of service through crafted IPv6 traffic; no confidentiality or integrity impact is stated.
Researcher notes
Key constraints: IPv6-specific, unauthenticated remote vector, high attack complexity, CWE-119, availability impact only. The source bundle does not include affected version ranges, fixed versions, or indicators of compromise, so validation depends on Cisco advisory details and local asset state.
Mitigation direction
- Check Cisco's advisory for affected release and fixed-release guidance.
- Prioritize review of ASR 5000/StarOS systems exposed to IPv6 traffic.
- Limit unnecessary IPv6 reachability to affected devices where operationally feasible.
- Monitor vendor guidance if version applicability is unclear.
Validation and detection
- Inventory Cisco ASR 5000 Series Software deployments.
- Confirm whether each deployment processes reachable IPv6 traffic.
- Compare installed StarOS releases with Cisco advisory applicability.
- Review reload history for unexplained availability events.
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-2020-3500 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
- Medium
- CVSS
- 6.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/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:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H2.24Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.8MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200805 Cisco StarOS IPv6 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.