Security readout for executives and security teams
Plain-English summary
Some Lenovo Personal Cloud Storage devices allowed an unauthenticated person on an adjacent network to create a normal user account. That could give unauthorized access to device functions or stored data, but the source bundle does not show remote internet exploitation or administrator compromise.
Executive priority
Prioritize if these devices store sensitive files or sit on shared networks. The issue is moderate severity, but unauthorized account creation can become a practical data-access problem in homes, branches, or small offices.
Technical view
CVE-2021-42851 is a CWE-862 missing authorization issue affecting Lenovo Personal Cloud Storage A1, T1, X1, T2, T2Pro. CVSS 3.1 is 6.3 with adjacent-network attack vector, low complexity, no privileges, no user interaction, and low confidentiality, integrity, and availability impact.
Likely exposure
Exposure is most likely where affected Lenovo personal cloud storage devices are reachable from untrusted local, Wi-Fi, or adjacent network segments. The source bundle lists affected models but does not specify firmware versions or CPE identifiers.
Exploitation context
The source bundle marks KEV as false and provides no evidence of active exploitation. Treat exploitation status as unconfirmed unless Lenovo, CISA, or another cited source later reports exploitation.
Researcher notes
Key gaps are affected firmware versions, patched versions, and detailed Lenovo remediation text. The CVSS vector limits attack scope to adjacent networks, so validation should focus on reachable local segments and account state, not internet-wide exposure assumptions.
Mitigation direction
- Check Lenovo advisory for model-specific firmware or configuration guidance.
- Apply only Lenovo-published updates or mitigations for affected devices.
- Restrict device access to trusted network segments only.
- Remove or disable unexpected standard user accounts.
- Retire unsupported devices if no vendor-supported fix is available.
Validation and detection
- Inventory Lenovo Personal Cloud Storage A1, T1, X1, T2, T2Pro devices.
- Confirm device model and firmware against Lenovo advisory details.
- Review user lists for unexpected standard accounts.
- Check logs for account-creation events, if available.
- Verify untrusted adjacent networks cannot reach device management functions.
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-862: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. 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-2021-42851 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 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
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:L/I:L/A:L2.83.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://iknow.lenovo.com.cn/detail/dc_200017.htmlCVE 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.
Missing Authorization
Missing Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.