Security readout for executives and security teams
Plain-English summary
CVE-2020-21016 is a critical remote code execution issue in D-Link DIR-846 firmware 100A35. A successful attacker could run arbitrary code as root, meaning full device compromise. The provided sources do not show CISA KEV listing or confirmed active exploitation.
Executive priority
Prioritize remediation where DIR-846 firmware 100A35 is deployed, especially at network edges or unmanaged sites. Root-level remote compromise of a router can enable traffic interception, persistence, and outage impact.
Technical view
The CVE describes CWE-94 code injection affecting D-Link DIR-846 firmware 100A35 through the HNAP1 SetGuestWLanSettings control path. CVSS 3.1 is 9.8, with network attack vector, low complexity, no privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited by the evidence to D-Link DIR-846 devices running firmware 100A35. Risk is highest where device management or HNAP functionality is reachable from untrusted networks. The source bundle does not identify other affected models or firmware versions.
Exploitation context
The public GitHub reference appears to document the vulnerability, but the bundle does not prove active exploitation. CISA KEV is false in the supplied data. Treat exploitability as serious because the CVSS vector requires no authentication or user interaction.
Researcher notes
Evidence is thin but consistent: CVE data names DIR-846 firmware 100A35, CWE-94, root RCE, and a specific HNAP control path. Do not broaden affected scope without vendor confirmation. No source in the bundle confirms a patch version or active exploitation.
Mitigation direction
- Identify D-Link DIR-846 devices and confirm firmware versions.
- Check D-Link security guidance for fixed firmware or retirement instructions.
- Restrict management and HNAP access to trusted networks only.
- Remove remote administration exposure from the internet where present.
- Replace unsupported devices if no vendor-supported fix is available.
Validation and detection
- Inventory all D-Link DIR-846 devices in owned networks.
- Confirm whether any device runs firmware 100A35.
- Review firewall rules for exposed router management services.
- Check vendor guidance before declaring remediation complete.
- Monitor affected devices for unexpected configuration changes or instability.
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-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-21016 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
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.dlink.com/en/security-bulletin/CVE reference
- https://github.com/dahua966/Routers-vuls/blob/master/DIR-846/GuestWLanSetting_RCE.mdCVE reference
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 Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.