Security readout for executives and security teams
Plain-English summary
This is a cross-site scripting issue in specific Microsoft Dynamics 365 Business Central updates. A logged-in attacker would need a user to interact with malicious content, potentially allowing limited data exposure or unauthorized changes in that user’s browser context. It is not listed as CISA KEV, and the provided sources do not show active exploitation.
Executive priority
Treat this as a planned remediation item, not an emergency, unless affected Business Central portals are broadly accessible or handle sensitive financial workflows. The main business risk is limited data exposure or unauthorized actions through a user’s session.
Technical view
CVSS 3.1 is 5.4: network attack vector, low complexity, low privileges required, user interaction required, changed scope, low confidentiality and integrity impact, no availability impact. Microsoft identifies the issue as affecting Dynamics 365 Business Central 2020 Release Wave 2 Update 17.10 and 2021 Release Wave 1 Update 18.5.
Likely exposure
Exposure is most likely in organizations running the listed Dynamics 365 Business Central versions: 17.0.0.0 under 2020 Release Wave 2 Update 17.10, or 18.0.0.0 under 2021 Release Wave 1 Update 18.5.
Exploitation context
The source bundle marks KEV as false. The CVSS vector indicates exploitation requires prior low-level privileges and user interaction. Exploit maturity is listed as proof-of-concept, but the provided sources do not document active exploitation or public weaponization.
Researcher notes
The available evidence is sparse: no CWE is listed, and the source bundle provides no vulnerable endpoint, payload details, or exploitation procedure. Keep analysis limited to the CVSS vector, affected Microsoft product versions, MSRC reference, and absence of KEV evidence.
Mitigation direction
- Check Microsoft’s MSRC advisory for the official update guidance.
- Upgrade affected Business Central instances using Microsoft-supported servicing channels.
- Prioritize systems exposed to many internal users or partner access.
- Review compensating controls for script injection and user-content handling.
- Train users to report suspicious links or unexpected Business Central content.
Validation and detection
- Inventory Business Central deployments and confirm exact update versions.
- Identify any instances matching versions 17.0.0.0 or 18.0.0.0.
- Verify whether Microsoft’s official fix is installed.
- Check security logs for suspicious user-driven Business Central activity.
- Confirm browser/session controls reduce impact from injected script execution.
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.
CVE-2021-40440 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
- 5.4 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C
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:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C2.32.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.4MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:P/RL:O/RC:C
Source materials
- CVE List V5 sourceCVE List V5
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40440CVE 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.