Security readout for executives and security teams
Plain-English summary
CVE-2018-21147 is a post-authentication stack overflow in specific NETGEAR routers and gateways. An attacker already authenticated with high privileges and adjacent network access could potentially compromise confidentiality, integrity, and availability. The issue is medium severity, but affected edge devices should be upgraded promptly because routers are sensitive control points.
Executive priority
Schedule this for near-term remediation on any affected router fleet. It is not documented as actively exploited in the provided sources, but successful compromise of network gateway devices can create broad downstream business risk.
Technical view
The CVE describes a stack-based buffer overflow reachable by an authenticated user on affected NETGEAR models. CVSS 3.0 is 6.8 with adjacent-network attack vector, low complexity, high privileges required, no user interaction, and high CIA impact. The source bundle does not provide vulnerable endpoint details, CWE mapping, or proof-of-concept information.
Likely exposure
Exposure is limited to listed NETGEAR models running firmware below fixed versions: D7800, R7500v2, R7800, R8900, R9000, WNDR4300v2, and WNDR4500v3. Risk is highest where router administration is reachable from untrusted local networks or shared environments.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The CVSS vector indicates exploitation requires adjacent network access and high-privilege authentication. Treat this as a credible post-authentication device compromise risk, not as confirmed internet-wide exploitation.
Researcher notes
Available public detail is sparse. The record identifies affected models, fixed version thresholds, and CVSS impact, but not the vulnerable function, request path, or exploit mechanics. Avoid assuming unauthenticated or remote internet exploitability from the supplied evidence.
Mitigation direction
- Upgrade affected NETGEAR devices to the fixed firmware versions or later.
- Follow the NETGEAR advisory for model-specific firmware guidance.
- Restrict administrative access to trusted management networks only.
- Disable remote administration unless explicitly required and protected.
- Replace devices that cannot run a fixed firmware version.
Validation and detection
- Inventory NETGEAR router models and current firmware versions.
- Compare firmware versions against the fixed versions in the CVE description.
- Confirm administrative interfaces are not exposed to untrusted networks.
- Review device access logs for unexpected administrative activity.
- Document unsupported or unpatchable devices for replacement planning.
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-2018-21147 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 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AC:L/AV:A/A:H/C:H/I:H/PR:H/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:H/S:U/UI:N0.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.8MediumVector: CVSS:3.0/AC:L/AV:A/A:H/C:H/I:H/PR:H/S:U/UI:N
Source materials
- CVE List V5 sourceCVE List V5
- https://kb.netgear.com/000059486/Security-Advisory-for-Post-Authentication-Stack-Overflow-on-Some-Gateways-and-Routers-PSV-2017-3158CVE 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.