Security readout for executives and security teams
Plain-English summary
This is a high-impact flaw in several older NETGEAR routers. An unauthenticated attacker on an adjacent network could trigger a stack-based buffer overflow, potentially compromising the device. Business urgency depends on whether affected models are still deployed and below the fixed firmware versions.
Executive priority
Treat as a high-priority legacy router exposure check. Immediate action is warranted if affected models remain in service below fixed firmware, especially in remote-office or shared-network environments.
Technical view
CVE-2018-21203 is a pre-authentication stack-based buffer overflow affecting NETGEAR R6100, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, and WNDR4500v3 before specified firmware versions. CVSS 3.0 is 8.8 with adjacent-network attack vector, no privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely in small office, branch, lab, or home-office networks still using the listed NETGEAR router models on outdated firmware. The bundle supports adjacent-network exposure; it does not establish internet-reachable exploitation.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation evidence. Risk remains serious because the flaw is pre-authentication, low complexity, and has high impact if an attacker reaches the adjacent network path.
Researcher notes
The CVE record lists product versions in the description, but the structured affected field is not populated usefully. No CWE is provided. Analysis is therefore based on the CVE description, CVSS vector, KEV status, and NETGEAR advisory reference.
Mitigation direction
- Upgrade affected NETGEAR routers to at least the fixed firmware versions listed in the CVE description.
- Check the NETGEAR advisory for current firmware guidance and device-specific instructions.
- Replace unsupported affected devices if fixed firmware is unavailable.
- Restrict untrusted access to networks where affected routers are reachable.
- Prioritize branch, remote-office, and lab routers that may be poorly inventoried.
Validation and detection
- Inventory NETGEAR R6100, R9000, WNDR3700v4, WNDR4300, WNDR4300v2, and WNDR4500v3 devices.
- Compare installed firmware against the fixed versions listed in the CVE description.
- Confirm whether affected devices are reachable from adjacent or guest networks.
- Review change records for completed firmware updates or device replacement.
- Document any exceptions and compensating network controls.
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.
CVE-2018-21203 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
- 8.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AC:L/AV:A/A:H/C:H/I:H/PR:N/S:U/UI:N
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/AC:L/AV:A/A:H/C:H/I:H/PR:N/S:U/UI:N2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/AC:L/AV:A/A:H/C:H/I:H/PR:N/S:U/UI:N
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.netgear.com/000055146/Security-Advisory-for-Pre-Authentication-Stack-Overflow-on-Some-Routers-PSV-2017-2589CVE reference · x_refsource_CONFIRM
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.