Security readout for executives and security teams
Plain-English summary
A vulnerable WordPress plugin can let an attacker trick a site user into causing stored malicious script to be saved through Easy Registration Forms. That script could later run in visitors' or administrators' browsers. The issue is rated high, but the provided sources do not show active exploitation.
Executive priority
Prioritize remediation for public WordPress sites because stored XSS can affect visitors, administrators, trust, and data exposure. Urgency is high where the plugin is installed and actively used.
Technical view
Easy Registration Forms up to and including 2.1.1 lacks nonce validation in ajax_add_form in includes/class-form.php. The reported impact is CSRF leading to stored XSS, with CVSS 3.1 score 8.8 and vector AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
Likely exposure
Known exposure is WordPress sites running Easy Registration Forms versions up to and including 2.1.1. The source bundle does not identify other affected products, CPEs, or hosting-specific exposure conditions.
Exploitation context
The CVSS vector indicates network reachability, low attack complexity, no attacker privileges, and required user interaction. KEV is false, and the provided sources do not state active exploitation or provide confirmed exploitation in the wild.
Researcher notes
Evidence is limited to the CVE description, Wordfence advisory reference, and WordPress Trac code reference. The bundle identifies the vulnerable function and file, but does not include a named patch version, exploit telemetry, or detailed remediation steps.
Mitigation direction
- Inventory WordPress sites for Easy Registration Forms installations.
- Identify whether installed versions are 2.1.1 or older.
- Check vendor and Wordfence guidance for an official fixed version or remediation.
- Disable or remove affected plugin instances if no safe supported version is confirmed.
Validation and detection
- Verify plugin versions from WordPress administration or asset inventory records.
- Review plugin code or changelog for added nonce validation around ajax_add_form.
- Inspect site content for unexpected form changes or injected scripts.
- Review web and WordPress logs for suspicious plugin administration activity.
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-352: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2021-39353 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 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/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:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/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://www.wordfence.com/vulnerability-advisories/#CVE-2021-39353CVE reference · x_refsource_MISC
- https://plugins.trac.wordpress.org/browser/easy-registration-forms/tags/2.1.1/includes/class-form.php#L256CVE 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.
Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery (CSRF) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.