CVE-2026-52839 alextselegidis CVE debrief

Who should care

Users of Easy!Appointments, especially those hosting it, should be aware of this vulnerability and take steps to update and secure their installations. This includes reviewing and restricting appointment scheduling privileges, monitoring appointment logs for unauthorized changes, and implementing additional access controls to validate provider IDs in appointment requests. Security teams and vulnerability management teams should prioritize patching and review compensating controls for exposed systems while remediation is scheduled and verified. Platform operators and administrators should also review the affected scope and validate vendor guidance to ensure proper mitigation of this vulnerability. Additionally, asset inventory management and security monitoring teams may need to review relevant logs and detection systems to identify potential exploitation attempts.

Technical summary

Easy!Appointments versions prior to 1.6.0 have a vulnerability allowing an authenticated provider to inject new appointments into or reassign existing appointments to another provider's schedule. This is due to insufficient validation of the 'id_users_provider' field in the 'appointments/store' and 'appointments/update' endpoints. The issue was patched in version 1.6.0. A normal authenticated provider can exploit this vulnerability to manipulate appointments across different providers, potentially leading to unauthorized access or modifications. The vulnerability's impact is considered low, with a CVSS score of 3.3.

Defensive priority

Authenticated providers may face elevated risks due to insufficient validation in appointment scheduling.

Recommended defensive actions

• Review and update Easy!Appointments to version 1.6.0 or later
• Restrict appointment scheduling privileges to minimize cross-provider manipulation
• Monitor appointment logs for unauthorized changes
• Implement additional access controls to validate provider IDs in appointment requests
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability in Easy!Appointments versions prior to 1.6.0, where an authenticated provider could inject or reassign appointments across different providers due to inadequate validation. However, the scope of affected deployments and specific operational impacts are not detailed. Defenders should verify the presence of Easy!Appointments in their environment, review appointment scheduling privileges, and monitor logs for unauthorized changes. Additional review is needed to confirm the extent of potential exposure and validate vendor guidance.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.