Security readout for executives and security teams
Plain-English summary
CVE-2021-20103 affects AppNitro Machform before version 16. A file uploaded through a form could store unsafe script content because attachments were not sufficiently sanitized. If triggered, this could expose users or administrators viewing form submissions to browser-based compromise.
Executive priority
Prioritize remediation for public-facing Machform installations that accept attachments. Business risk is higher where staff routinely review submitted files or where sensitive user workflows depend on Machform.
Technical view
The vulnerability is stored cross-site scripting in Machform upload.php handling for form file attachments. The source bundle identifies all versions prior to version 16 as affected. No CVSS score, CWE, CPE, or detailed fix notes are provided.
Likely exposure
Exposure is likely where organizations run AppNitro Machform before version 16, especially internet-facing forms that allow file attachments.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Stored XSS is still relevant because malicious content may persist until viewed by staff or users.
Researcher notes
Evidence is limited to the CVE record and bundled Tenable/Machform reference. The bundle lacks CVSS, CWE, CPE, exploit details, and explicit mitigation text beyond the affected version boundary.
Mitigation direction
- Upgrade Machform to version 16 or later where feasible.
- Review vendor guidance and release notes for exact remediation details.
- Restrict file attachment uploads on public forms until remediated.
- Limit administrative access to form submissions to trusted users.
- Review uploaded attachment handling and sanitization controls.
Validation and detection
- Inventory Machform deployments and confirm installed versions.
- Identify forms using file attachment uploads through upload.php.
- Check whether affected systems are internet-facing.
- Perform controlled stored-XSS validation in staging only.
- Review recent submissions for suspicious attachment content.
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-2021-20103 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.tenable.com/security/research/tra-2021-25%2Chttps://www.machform.com/blog-machform-16-released/CVE 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.