CVE-2018-6339 in WhatsApp
Summary
by MITRE
When receiving calls using WhatsApp on Android, a stack allocation failed to properly account for the amount of data being passed in. An off-by-one error meant that data was written beyond the allocated space on the stack. This issue affects WhatsApp for Android starting in version 2.18.180 and was fixed in version 2.18.295. It also affects WhatsApp Business for Android starting in version v2.18.103 and was fixed in version v2.18.150.
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Analysis
by VulDB Data Team • 09/03/2025
The vulnerability described in CVE-2018-6339 represents a critical stack-based buffer overflow condition that specifically impacts WhatsApp for Android applications. This flaw manifests during the processing of incoming calls when the application fails to correctly calculate memory allocation for data handling on the stack. The issue stems from an off-by-one error in the stack allocation logic, where the application miscalculates the required memory space by exactly one byte, leading to memory corruption during data processing operations. The vulnerability affects both standard WhatsApp and WhatsApp Business applications on Android platforms, indicating a widespread impact across the messaging ecosystem.
The technical implementation of this vulnerability falls under the Common Weakness Enumeration category CWE-121, which specifically addresses stack-based buffer overflow conditions. This classification indicates that the flaw allows for data to be written beyond the bounds of allocated stack memory, potentially overwriting adjacent memory locations including return addresses, function parameters, and local variables. The off-by-one error creates a precise condition where a single byte of data is written beyond the intended memory boundaries, making the vulnerability both predictable and exploitable. The specific nature of the flaw suggests that attackers could manipulate incoming call data to trigger the overflow condition, potentially leading to arbitrary code execution within the application context.
From an operational perspective, this vulnerability presents a significant security risk to users of affected WhatsApp applications, as it could be exploited through social engineering attacks or by sending specially crafted call data to trigger the buffer overflow. The exploitation potential extends beyond simple application crashes to include more severe consequences such as remote code execution, allowing attackers to gain unauthorized access to device resources. The vulnerability's impact is particularly concerning given WhatsApp's widespread usage and the sensitive nature of communication data handled by the application. The fact that both standard and business versions of the application are affected suggests that the flaw exists in core application components rather than being isolated to specific features or user interfaces.
The mitigation strategy for this vulnerability involves immediate deployment of the patched versions of WhatsApp applications, specifically version 2.18.295 for standard WhatsApp and version 2.18.150 for WhatsApp Business. Users should ensure their applications are updated to the latest versions to eliminate the risk of exploitation. System administrators and security professionals should also implement monitoring for potential exploitation attempts and consider network-based detection measures to identify suspicious call data patterns that might indicate attempts to leverage this vulnerability. Additionally, organizations should conduct vulnerability assessments to verify that all affected devices within their environment have been properly updated and that no legacy versions remain in use, as the vulnerability could potentially be exploited in enterprise environments where multiple devices are managed centrally.