Security readout for executives and security teams
Plain-English summary
This flaw could let an attacker read sensitive information stored insecurely by QNAP myQNAPcloud Link. The business risk is data exposure on affected NAS systems, not system takeover based on the supplied CVSS data.
Executive priority
Treat as a targeted remediation item for QNAP NAS assets, especially where remote access is enabled. Prioritize confirming versions and upgrading affected systems, but current supplied evidence does not justify emergency incident assumptions.
Technical view
CVE-2021-28815 is CWE-922 insecure storage in QNAP myQNAPcloud Link before 2.2.21 on listed QTS, QuTS hero, and QuTScloud releases. CVSS 3.1 is 6.0 with high confidentiality impact and no integrity or availability impact.
Likely exposure
Exposure is limited to QNAP NAS environments running myQNAPcloud Link before 2.2.21 on QTS 4.5.3, QuTS hero h4.5.2, or QuTScloud c4.5.4.
Exploitation context
The bundle does not show CISA KEV listing or confirmed active exploitation. The description says remote attackers, while the CVSS vector indicates local access with high privileges; verify against QNAP guidance.
Researcher notes
Key uncertainty is access model: the prose says remote attackers, but CVSS lists AV:L and PR:H. Do not assume internet-exploitable unauthenticated access from this bundle alone. Focus validation on version state, deployment exposure, and sensitive data handling.
Mitigation direction
- Identify QNAP systems using myQNAPcloud Link.
- Upgrade myQNAPcloud Link to 2.2.21 or later where supported.
- Review QNAP advisory QSA-21-26 for product-specific instructions.
- Limit NAS exposure and remote access to trusted users.
- Rotate secrets if sensitive data exposure is suspected.
Validation and detection
- Inventory QNAP NAS firmware and myQNAPcloud Link versions.
- Confirm affected platforms: QTS 4.5.3, QuTS hero h4.5.2, or QuTScloud c4.5.4.
- Verify myQNAPcloud Link is 2.2.21 or later.
- Check whether myQNAPcloud Link is enabled on externally reachable systems.
- Review logs for unusual access to sensitive configuration or storage data.
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-922: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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-2021-28815 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 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:N/A: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:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N1.54Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6MediumVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.qnap.com/zh-tw/security-advisory/qsa-21-26CVE 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.
Insecure Storage of Sensitive Information
Insecure Storage of Sensitive Information represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.