Security readout for executives and security teams
Plain-English summary
CVE-2021-40377 is a stored cross-site scripting issue in SmarterTools SmarterMail 16.x before build 7866. Malicious email content could be stored and later rendered by the application, potentially affecting users who view it. Public source data does not provide CVSS, CWE, or confirmed exploitation evidence.
Executive priority
Treat this as a near-term remediation item if SmarterMail 16.x is present. The issue can affect users through stored email content, but public evidence does not show active exploitation or a quantified severity score.
Technical view
The vulnerability is caused by insufficient sanitization of email content in SmarterMail 16.x before build 7866. The CVE description states HTML and/or JavaScript can be injected into a page, then processed and stored by the application. Available sources do not specify privileges, attack complexity, affected CPEs, or impact scope.
Likely exposure
Exposure is most likely for organizations still running SmarterMail 16.x builds earlier than 7866, particularly where users access email through the web application. The provided CVE data lists generic affected fields as unavailable, so inventory should rely on installed product and build information.
Exploitation context
The source bundle does not cite CISA KEV inclusion, public exploitation, or exploit availability. Risk comes from stored XSS behavior in an email platform, where malicious content may persist and affect later viewers. Evidence is incomplete beyond the CVE description and vendor release-note reference.
Researcher notes
Source data lacks CVSS, CWE, CPEs, exploit details, and detailed vendor advisory text. The key grounded facts are product line, fixed build boundary, and stored XSS through unsanitized email content. Avoid assuming impact beyond browser-side script execution risk.
Mitigation direction
- Identify any SmarterMail 16.x deployments and record exact build numbers.
- Update affected SmarterMail 16.x systems to build 7866 or later.
- Review SmarterTools release notes for vendor-specific remediation guidance.
- Limit access to vulnerable webmail interfaces until remediation is complete.
Validation and detection
- Confirm production SmarterMail build numbers are 7866 or later.
- Check asset inventory for any remaining SmarterMail 16.x installations.
- Review vendor release notes for the fixed build boundary.
- Monitor support tickets or security logs for suspicious webmail rendering issues.
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-2021-40377 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.smartertools.com/smartermail/release-notes/currentCVE 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.