GHSA-4vmm-5qvc-w5p7 is a high-severity (CVSS 7.1) Information Exposure vulnerability in alextselegidis/easyappointments. O3 Security confirms whether GHSA-4vmm-5qvc-w5p7 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Easy!Appointments Vulnerable to Appointments Takeover via Excessive Data Exposure
Real-World Exposure
alextselegidis/easyappointmentsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
An Excessive Data Exposure vulnerability in the customers search endpoint allows an authenticated user to obtain appointment hashes belonging to other users. Using these hashes, an attacker can modify or delete appointments of other providers, resulting in an Appointments Takeover.
Details
The customers search endpoint exposes excessive information, including appointment hashes, to any authenticated user without proper authorization checks. These hashes uniquely identify appointments that do not belong to the searching user.
By reusing the obtained hashes, an attacker can interact with appointment management endpoints, allowing the modification or deletion of third-party appointments.
The lack of object-level authorization controls leads to an Appointments Takeover, impacting data confidentiality and integrity.
Impact
This vulnerability allows an authenticated user to take control of appointments belonging to other users. By obtaining and reusing the exposed hashes, an attacker can view, modify, or delete appointments of other providers, compromising data integrity and confidentiality. This may result in unauthorized appointment cancellations or modifications, operational disruption of the service.
PoC
- Let's start by viewing an appointment with the provider “Jane Doe.”
- Now, with the provider “test test” (another provider), let's send the request to /customers/search, where we can verify that the customer “Joe Shmoe” is on the list. This makes it possible to extract the hash of the appointment associated with the user Jane Doe, because the response is returning excessive data.
- With this hash, we then go to the endpoint /calendar/reschedule/{hash} with the provider “test test,” where we can check some information about the appointment.
- By changing the provider to “test test,” it is possible to change the appointment provider.
- By saving, we can verify that the appointment is now in the “test test” provider, thus disappearing from the “John Doe” provider calendar.
Provider "test test" Calendar:
<img width="1916" height="879" alt="image" src="https://github.com/user-attachments/assets/77b9e11a-860f-4c08-847e-fa95c064710d" />Provider "John Doe" Calendar:
<img width="1917" height="880" alt="image" src="https://github.com/user-attachments/assets/d39566f5-a58c-4337-a781-0886faa83c12" />5.1. Since we have takeover the appointment, it is possible to cancel/delete it.
<img width="1486" height="736" alt="image" src="https://github.com/user-attachments/assets/2a87b9d0-1726-4fdc-af72-7ae9e20cc050" /> <img width="290" height="867" alt="image" src="https://github.com/user-attachments/assets/815b1df6-dfd4-437a-a2bd-e9b61832d5b0" />Recommendation
When making the POST request to the /customers/search endpoint, only return appointments that belong to the provider sending the request. This way, the provider does not have access to the random hash and cannot perform the takeover.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | alextselegidis/easyappointments | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for alextselegidis/easyappointments. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of alextselegidis/easyappointments has shipped for GHSA-4vmm-5qvc-w5p7 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-4vmm-5qvc-w5p7 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-4vmm-5qvc-w5p7. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-4vmm-5qvc-w5p7 in your dependencies?
O3 detects GHSA-4vmm-5qvc-w5p7 across Packagist dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.