Security readout for executives and security teams
Plain-English summary
CVE-2018-21156 is a post-authentication buffer overflow affecting many NETGEAR gateways, routers, and extenders running older firmware. An attacker would need high privileges and adjacent-network access, but successful abuse could severely affect confidentiality, integrity, and availability on the device.
Executive priority
Treat as a scheduled remediation item, not an emergency, unless affected devices manage sensitive networks or use shared admin credentials. The impact could be high, but access requirements reduce immediate likelihood.
Technical view
The CVSS 3.0 vector is AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, score 6.8. Sources describe an authenticated buffer overflow across listed NETGEAR models before specific firmware versions. No CWE details or exploit mechanism are provided in the bundle.
Likely exposure
Exposure is most likely where listed NETGEAR devices remain on firmware below the documented fixed versions. Risk is constrained by adjacent-network access and high privileges, but many consumer and small-office models are named.
Exploitation context
The source bundle does not show CISA KEV listing or cited active exploitation. Because exploitation requires authentication with high privileges, prioritize environments where admin access is broadly shared or device management networks are weakly controlled.
Researcher notes
Evidence is limited to the CVE record and NETGEAR advisory reference. The bundle names affected models and version thresholds, but does not include root cause details, exploit primitives, proof of concept, or confirmed exploitation.
Mitigation direction
- Inventory NETGEAR models against the affected device list.
- Upgrade affected devices to the listed fixed firmware version or later.
- Use NETGEAR’s advisory and support pages for current firmware guidance.
- Limit administrative access to trusted administrators only.
- Follow vendor guidance for devices without available fixed firmware.
Validation and detection
- Compare each device model and firmware version with the CVE description thresholds.
- Confirm upgraded devices report fixed firmware versions or later.
- Review who has administrative access to affected devices.
- Check scanner findings against the exact NETGEAR model list.
- Document any unsupported or unpatched devices as residual risk.
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-2018-21156 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/000059474/Security-Advisory-for-Post-Authentication-Buffer-Overflow-on-Some-Gateways-Routers-and-Extenders-PSV-2017-2460CVE 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.