CVE-2026-52839: Auth Bypass (CVSS 3.3)

Description

Easy!Appointments is a self hosted appointment scheduler. Versions prior to 1.6.0 correctly filter provider-scoped appointments in the `appointments/search` response, proving that provider isolation is an intended security boundary. However, the direct mutation endpoints `appointments/store` and `appointments/update` only check generic appointment privileges and never verify that the submitted `id_users_provider` belongs to the current session. A normal authenticated provider can inject new appointments into another provider's schedule via `store`, or reassign existing appointments into a foreign provider's calendar via `update`. The `store` path contains an additional write-before-crash bug: the unauthorized row is committed to the database before the controller crashes on a type error, so the attacker receives an error response while the foreign appointment is already persisted. Version 1.6.0 patches the issue.

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CVSS v3.1 Score

3.3

LOW

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N

EPSS — Exploit Prediction

0.0015

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-639 CWE-639

CWE-862 Missing Authorization

References

Other References

https://github.com/alextselegidis/easyappointments/commit/4abb10545d83ac1a57d03f6502376ee67696ea7c https://github.com/alextselegidis/easyappointments/security/advisories/GHSA-w8xc-8g92-v77h https://github.com/alextselegidis/easyappointments/security/advisories/GHSA-w8xc-8g92-v77h

Frequently Asked Questions

What is CVE-2026-52839? +

Easy!Appointments is a self hosted appointment scheduler. Versions prior to 1.6.0 correctly filter provider-scoped appointments in the `appointments/search` response, proving that provider isolation is an intended security boundary. However, the direct mutation endpoints `appointments/store` and `appointments/update` only check generic appointment privileges and never verify that the submitted `id_users_provider` belongs to the current session. A normal authenticated provider can inject new appointments into another provider's schedule via `store`, or reassign existing appointments into a foreign provider's calendar via `update`. The `store` path contains an additional write-before-crash bug: the unauthorized row is committed to the database before the controller crashes on a type error, so the attacker receives an error response while the foreign appointment is already persisted. Version 1.6.0 patches the issue. It has a CVSS v3.1 base score of 3.3 (LOW).

How severe is CVE-2026-52839? +

CVE-2026-52839 has a CVSS v3.1 score of 3.3 out of 10, rated LOW. This is a low-severity vulnerability with limited impact. The EPSS score is 0.0015, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-52839? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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