Recently, an exposure of sensitive information to an unauthorized actor has been discovered in Outlook for Android (CVE-2025-29805). This vulnerability allows an unauthorized attacker to disclose information over a network, potentially causing devastating consequences for users and organizations alike. In this article, we will discuss what has been discovered about this vulnerability, how it works, and what you can do to protect yourself and your organization from potential attacks.

Background

The Common Vulnerabilities and Exposures (CVE) project has assigned the identifier CVE-2025-29805 to this specific issue. You can find more information about this vulnerability in the National Vulnerability Database (NVD) entry, which is available at the following link:

https://nvd.nist.gov/vuln/detail/CVE-2025-29805

The Exposure

The vulnerability in question affects the Outlook for Android application, which is a widely-used email client for managing emails, calendars, contacts, and tasks from any email accounts. The issue allows an attacker with unauthorized access to disclose sensitive information over a network, thus breaching user privacy and potentially causing damage to the affected individuals and organizations.

The vulnerability itself stems from improper handling of sensitive data within the application's communication with the server. This allows attackers to intercept and access sensitive information, such as emails, passwords, and even file attachments.

Code Snippet

To better illustrate the issue, let's take a look at a simplified code snippet that represents the problematic communication between the Outlook for Android application and an email server:

import requests

url = "https://email.example.com/api/messages";
headers = {
   "Content-Type": "application/json",
   "Authorization": "Basic YWAKjl4dhslTm20="
}
data = {
   "email": "user@example.com",
   "password": "MySuperSecurePassword"
}

response = requests.post(url, headers=headers, data=data)

In the above code snippet, the email address and password are sent to the email server using the "Authorization" header, which is common practice. However, the issue lies in the fact that the same sensitive information is included in the unencrypted "data" payload, thus exposing it to potential interception by attackers.

Exploit Details

An attacker exploiting this vulnerability would most likely perform a man-in-the-middle (MITM) attack, where they intercept the communication between the Outlook for Android application and the email server. By doing so, they can access the sensitive information contained within the unencrypted "data" payload.

Once an attacker has access to this information, they could potentially perform various actions, such as:

1. Reading the intercepted emails and file attachments, leading to a breach of privacy and potential exposure of critical or sensitive information.
2. Using the stolen credentials (email address and password) to gain unauthorized access to the affected user's email account, enabling further malicious activities like sending spam, phishing emails, or even conducting identity theft.

Mitigation Steps

To protect yourself and your organization from potential attacks exploiting this vulnerability, consider the following steps:

1. Update your Outlook for Android application to the latest version, as this vulnerability may be addressed in a future update by Microsoft.
2. Use a Virtual Private Network (VPN) or an encrypted connection when connecting to the internet, in order to minimize the risks of MITM attacks.
3. Encourage your organization to implement strong security protocols, such as Multi-Factor Authentication (MFA), to reduce the risks of unauthorized access to user accounts even if credentials are exposed.

Conclusion

CVE-2025-29805 is a concerning vulnerability that can lead to the exposure of sensitive information to unauthorized actors in Outlook for Android. By understanding the vulnerability and taking proper mitigation steps, users and organizations can protect themselves from potential attacks and minimize the risk of data breaches.

Timeline

Published on: 04/08/2025 18:16:06 UTC
Last modified on: 05/06/2025 17:03:53 UTC