CVE-2026-70638 in llama.cpp
Summary
by MITRE • 08/07/2026
llama.cpp builds b1886 through b7445 contain an integer overflow vulnerability in the LLaMA-Android JNI wrapper where the new_1batch() function multiplies sizeof(llama_seq_id) by an attacker-controlled n_seq_max parameter without overflow validation, causing heap buffer allocation to wrap and allocate insufficient memory. Attackers can exploit this by providing a crafted n_seq_max value through a malicious model file or JNI call to trigger heap corruption and achieve denial of service or arbitrary code execution on Android applications using the LLaMA-Android binding.
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Analysis
by VulDB Data Team • 08/07/2026
The vulnerability exists within the llama.cpp library version range b1886 through b7445 specifically affecting the LLaMA-Android JNI wrapper implementation. This integer overflow occurs in the new_1batch() function where the code performs a multiplication operation between sizeof(llama_seq_id) and an attacker-controlled parameter n_seq_max without implementing proper overflow validation mechanisms. The flaw represents a classic integer overflow condition that can be exploited through improper input validation.
The technical exploitation mechanism relies on the attacker controlling the n_seq_max parameter through either a malicious model file or direct JNI calls to the Android binding interface. When this parameter is manipulated to extremely large values, the multiplication operation causes the resulting heap allocation size to wrap around due to integer overflow, leading to allocation of insufficient memory for the intended buffer. This memory corruption scenario creates opportunities for attackers to manipulate heap structures and potentially achieve arbitrary code execution.
From a cybersecurity perspective, this vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions that can lead to buffer overflows and memory corruption. The ATT&CK framework categorizes this as a software vulnerability exploitation technique under the T1210 - Exploitation of Remote Services or T1059 - Command and Scripting Interpreter categories, depending on the execution context. The Android-specific nature places this vulnerability within the mobile application security domain where JNI bindings present additional attack surface considerations.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enable complete system compromise when exploited successfully. Applications using the LLaMA-Android binding become susceptible to heap corruption attacks that could allow remote code execution, particularly in scenarios where the vulnerable library is integrated into mobile applications processing untrusted model files or user input through JNI interfaces. The vulnerability affects Android applications that rely on the LLaMA-Android wrapper for their machine learning inference capabilities.
Mitigation strategies should focus on implementing proper integer overflow validation before memory allocation operations within the new_1batch() function. Input sanitization of the n_seq_max parameter to enforce reasonable bounds and prevent excessive values from propagating to the multiplication operation represents the primary defense mechanism. Additionally, applications should implement proper error handling for memory allocation failures and consider using safe integer arithmetic libraries or compiler flags that enable overflow detection. Updates to the affected library versions should be prioritized, and security patches addressing the specific integer overflow condition in the JNI wrapper implementation must be deployed across all affected Android applications utilizing the LLaMA-Android binding.