Security readout for executives and security teams
Plain-English summary
CVE-2018-21121 is an authentication bypass affecting certain NETGEAR switches. A nearby attacker may be able to access protected functionality without credentials, risking device configuration, network availability, and confidentiality. The listed affected models are GS810EMX, XS512EM, and XS724EM below specific firmware versions.
Executive priority
Treat as high priority for environments using these NETGEAR switches, especially where management access is broadly reachable on internal networks. Remediation is firmware-focused and should be scheduled promptly after asset confirmation.
Technical view
The CVE describes authentication bypass on NETGEAR GS810EMX before 1.0.0.5, XS512EM before 1.0.0.6, and XS724EM before 1.0.0.6. CVSS 3.0 is 8.8 with adjacent-network attack vector, low complexity, no privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely where affected switch management interfaces are reachable from the same local or adjacent network segment. Internet exposure is not stated in the sources and should not be assumed.
Exploitation context
The bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector indicates exploitation requires adjacent-network access, not valid credentials or user interaction.
Researcher notes
The provided affected-product fields are sparse, but the CVE description names models and fixed-version thresholds. No CWE, exploit details, or public exploitation evidence are provided in the bundle.
Mitigation direction
- Upgrade GS810EMX firmware to 1.0.0.5 or later.
- Upgrade XS512EM and XS724EM firmware to 1.0.0.6 or later.
- Confirm firmware and remediation guidance against the NETGEAR advisory.
- Restrict switch management access to trusted administrative networks.
Validation and detection
- Inventory NETGEAR GS810EMX, XS512EM, and XS724EM devices.
- Record running firmware versions for each affected switch model.
- Compare versions against the fixed releases listed by NETGEAR.
- Review network access controls for switch management interfaces.
- Check device logs and configuration history for unexpected administrative changes.
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.
Credential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2018-21121 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/000060237/Security-Advisory-for-Authentication-Bypass-on-Some-Switches-PSV-2018-0219CVE 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.