Security readout for executives and security teams
Plain-English summary
This affects obsolete D-Link DVG-3104MS VoIP gateway firmware. The device includes undocumented accounts with hard-coded, weak credentials. If an attacker can reach the device on the same network segment, they may gain unauthorized access with serious confidentiality, integrity, and availability impact.
Executive priority
Treat this as a high-priority legacy-device risk. The device is unsupported, the issue involves hidden credentials, and remediation should focus on removal, replacement, or strong isolation.
Technical view
CVE-2021-39613 is CWE-798 in D-Link DVG-3104MS firmware 1.0.2.0.3, 1.0.2.0.4, and 1.0.2.0.4E. Undocumented user accounts are present in /etc/passwd, and weak password hashes allow plaintext recovery. CVSS 3.1 is 8.8 with adjacent-network attack vector and no required privileges or user interaction.
Likely exposure
Exposure is limited to organizations still operating unsupported D-Link DVG-3104MS devices on the affected firmware versions, especially where management or device access is reachable from internal networks.
Exploitation context
The source bundle does not show CISA KEV listing or confirmed active exploitation. The CVSS vector indicates exploitation requires adjacent network access, but the impact is high if the device is reachable.
Researcher notes
Evidence supports hard-coded undocumented accounts and weak recoverable hashes. Product support has ended. The bundle does not identify a current patch, public exploitation, or broader affected product families.
Mitigation direction
- Identify any D-Link DVG-3104MS devices and firmware versions in inventory.
- Retire or replace affected end-of-support devices where possible.
- Review D-Link security guidance for any vendor-stated options.
- Isolate remaining devices from user and untrusted network segments.
- Restrict management and device access to explicitly authorized hosts.
- Do not rely solely on changing documented admin passwords.
Validation and detection
- Confirm whether DVG-3104MS exists in asset inventory or network scans.
- Verify firmware is not 1.0.2.0.3, 1.0.2.0.4, or 1.0.2.0.4E.
- Check network controls limiting access to the device.
- Review logs for unexpected management access or unknown account activity.
- Document replacement or compensating controls for unsupported devices.
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-798: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. 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 lookupCVE-2021-39613 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 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/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:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:A/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 · x_refsource_MISC
- https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10237CVE reference · x_refsource_MISC
- https://www.nussko.com/advisories/advisory-2021-08-01.txtCVE reference · x_refsource_MISC
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.
Use of Hard-coded Credentials
Use of Hard-coded Credentials represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.