Open-Source Security Intelligence

Know every vulnerability
before it knows you.

DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.

Checkout DevGuard View on GitHub

GHSA-4vmm-5qvc-w5p7

HighCVSS 7.1 / 10

Published Jul 29, 2026·Last modified Jul 29, 2026

Affected Components(0)

No affected components available

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:

Provider "John Doe" Calendar:

5.1. Since we have takeover the appointment, it is possible to cancel/delete it.

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.

Risk Scores

Base Score

7.1

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information. There is a high impact on the integrity of the data.

Threat Intelligence

6.5

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS

0.18%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit

Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Browse More

High severity

Scan your project

Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.

Checkout DevGuard