Security readout for executives and security teams
Plain-English summary
A malicious Excel-style spreadsheet can crash or take over WPS Spreadsheets in WPS Office 11.2.0.10351. The attacker must convince a user to open the malformed XLS file. Business risk is highest where WPS Office is used for external spreadsheet handling.
Executive priority
Treat as high priority if WPS Office is deployed. The issue can lead to code execution, but it requires user interaction and there is no cited evidence of active exploitation.
Technical view
CVE-2021-40399 is a CWE-416 use-after-free in WPS Spreadsheets (ET), part of WPS Office 11.2.0.10351. The CVSS 3.0 score is 8.8 with low complexity, no privileges required, and user interaction required. Successful exploitation may result in code execution with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure appears limited to endpoints running WPS Office 11.2.0.10351, especially users who receive and open XLS files from email, web downloads, or external partners.
Exploitation context
The source bundle says exploitation requires a specially crafted XLS file opened by the victim. KEV is false, and the provided sources do not establish active exploitation in the wild.
Researcher notes
Evidence is specific to WPS Office 11.2.0.10351 and malformed XLS handling. The provided bundle does not name a fixed version or detailed mitigation, so remediation should be tied to WPS guidance.
Mitigation direction
- Inventory endpoints for WPS Office 11.2.0.10351.
- Check WPS vendor guidance for the fixed or supported version.
- Update affected WPS Office installations when a vendor-supported fix is confirmed.
- Block or quarantine unsolicited XLS files where business workflows allow.
- Use email and endpoint controls to inspect spreadsheet attachments.
Validation and detection
- Confirm whether WPS Spreadsheets ET is installed on user endpoints.
- Verify installed WPS Office versions against 11.2.0.10351.
- Review email and download telemetry for suspicious XLS delivery attempts.
- Confirm endpoint protection covers malicious spreadsheet behavior.
- Document vendor advisory status before closing remediation.
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-416: 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-40399 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/AV:N/AC:L/PR:N/UI:R/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:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://talosintelligence.com/vulnerability_reports/TALOS-2021-1412CVE reference · x_refsource_MISC
- https://security.wps.cn/notices/28CVE 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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.