Critical Microsoft Teams Android Vulnerability Exposes User Data

Key Takeaways

• A critical vulnerability, CVE-2026-42835, has been identified in Microsoft Teams for Android.
• The flaw allows an authenticated attacker to remotely expose sensitive data from heap memory.
• Rated with a CVSS 3.1 score of 8.1, the vulnerability poses a significant risk to user confidentiality and application availability.
• A security update is available via the Google Play Store, and immediate patching is strongly recommended.

Microsoft Teams Android Flaw Exposes Sensitive User Data

Microsoft has recently disclosed a significant security vulnerability affecting its Teams application for Android devices. Designated as CVE-2026-42835, this flaw presents a risk of sensitive information disclosure over a network by an authenticated adversary. The details of this “Important” severity vulnerability were made public on June 9, 2026.

Technical Details of the Vulnerability

The core issue behind CVE-2026-42835 lies in the improper handling of special characters within output that is then processed by a subsequent component. This type of weakness is categorized under CWE-74, often referred to as an Injection vulnerability.

According to Microsoft’s official advisory, an attacker with valid authentication can exploit this weakness to remotely extract information without requiring any user interaction on the target device.

Severity and Potential Impact

The vulnerability carries a CVSS 3.1 base score of 8.1, with a temporal score of 7.1, underscoring its serious nature. The attack vector is classified as Network (AV:N), confirming that it can be exploited remotely over the internet. Furthermore, the attack complexity is rated as Low (AC:L), indicating that attackers do not need advanced technical expertise and can achieve reliable exploitation with a specifically crafted payload targeting the vulnerable component.

Microsoft has confirmed that successful exploitation could enable an attacker to read small segments of heap memory. While seemingly limited in scope, heap memory is critical, often containing highly sensitive runtime data such as authentication tokens, active session IDs, or cached credentials. Even partial exposure of such data constitutes a significant security risk, particularly within corporate environments where Teams is extensively used.

The CVSS metrics highlight a high impact on both Confidentiality and Availability, although integrity remains unaffected. The privileges required for exploitation are rated as Low, meaning that even accounts with minimal permissions could potentially trigger this vulnerability.

Exploitation Status and Remediation

Despite its severity, Microsoft’s assessment indicates that exploitation of CVE-2026-42835 is “Less Likely.” As of the publication date, there has been no public disclosure of the flaw, nor has it been observed under active exploitation. The exploit code maturity is currently listed as “Unproven.” Crucially, an official fix for this vulnerability is already available.

Microsoft has released a security update for Microsoft Teams for Android. This update is accessible through the Google Play Store. Users and enterprise administrators are strongly urged to update the application immediately via the official Microsoft Teams listing on Google Play.

Organizations that rely on Microsoft Teams for critical internal communications should prioritize this update. Given the application’s role in handling sensitive business conversations and file sharing, addressing this vulnerability promptly is essential for maintaining enterprise security.

The vulnerability was responsibly identified and reported by Ofek Levin of Enclave, who submitted the finding through Microsoft’s coordinated vulnerability disclosure program.

What You Should Do

• Update Immediately: Ensure your Microsoft Teams for Android application is updated to the latest version available on the Google Play Store.
• Enable Automatic Updates: Configure your Android device to automatically update applications to receive security patches as soon as they are released.
• Educate Users: Inform employees about the importance of keeping their applications updated, especially those used for business communications.
• Monitor for Anomalies: Maintain vigilance for any unusual network activity or unauthorized access attempts within your environment, particularly involving Teams usage.

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