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CVE-2026-13400 - Before 1 Plugin

CVE-2026-13400

Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4's wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time.

CVE-2026-13400

UNKNOWN CVSS 0.0 Published 2026-07-27 Updated 2026-07-27
AI Risk Low (6/100) Active Exploit: No strong signal Published Exploit: No public exploit references Priority: P5 Monitor
Severity Band UNKNOWN
CVSS Vector Unspecified
Affected Components 2
Reference Links 1
AI Risk Engine Low (6/100)
Exploitability Low
Active Exploitation No strong signal
Published Exploit Status No public exploit references

Threat Timeline

  1. 2026-07-27 CVE published and first recorded in the threat feed.
  2. 2026-07-27 Record updated with latest vulnerability metadata.
  3. 2026-07-27 AI technical context refreshed for mitigation and impact guidance.
  4. Now Monitoring for follow-up changes, linked references, and new related CVEs.

AI Context

Machine-generated threat intelligence

AI Updated just now

AI enriched just now (2026-07-27 20:15 UTC)

Technical Summary

Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4's wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time.

Potential Impact

Severity is UNKNOWN (CVSS 0.0). Depending on deployment context, affected components may be exposed to unauthorized actions or data integrity risk.

Exploitability Assessment

Exploitability is assessed as Low based on low-bar exploit prerequisites.

Primary risk drivers: low-bar exploit prerequisites

Mitigation Recommendations

Validate affected product versions, prioritize patching, and monitor references for vendor remediation guidance. If immediate patching is not possible, apply compensating controls and limit exposure of vulnerable surfaces.

Detection & Monitoring

Track authentication anomalies, unexpected file writes, and suspicious plugin API activity around affected components.

Business Impact Lens

AI risk score 6/100 (Low, Low) with priority P5 Monitor. Prioritize remediation where affected components process customer data, admin sessions, or Internet-exposed workflows.

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