CVE-2026-86314 in Walrus
Summary
by MITRE • 09/07/2026
Integer overflow in the source-bounds check in Memory::init() (src/runtime/Memory.cpp) in Samsung walrus on all platforms allows a remote attacker to cause an out-of-bounds heap read and denial of service via a crafted WebAssembly module in which a 32-bit unsigned addition wraps around and bypasses the bounds check.
This issue affects Walrus: ff3bf5ff5c4878f8e5572c9593d303f6bc997443.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 09/07/2026
The vulnerability identified in Samsung's walrus WebAssembly runtime represents a critical security flaw rooted in improper integer arithmetic during memory initialization operations. Specifically, the defect resides within the source-bounds check logic implemented in the Memory::init function located in src/runtime/Memory.cpp. This component is responsible for validating that data being written to or read from the WebAssembly linear memory does not exceed allocated boundaries. The core technical failure occurs when a 32-bit unsigned addition operation wraps around due to integer overflow, effectively bypassing these critical bounds checks. In systems relying on fixed-width integers, such as those using uint32_t types common in low-level runtime implementations, adding two large values can result in a value that appears smaller than the original operands or falls below expected threshold limits when interpreted against memory size constraints. This arithmetic anomaly allows an attacker to craft inputs where the calculated offset passes validation despite actually pointing outside the allocated heap region.
From an operational perspective, this flaw enables remote attackers to trigger out-of-bounds heap reads by submitting specially crafted WebAssembly modules through web interfaces or applications that utilize the walrus runtime for executing untrusted code. The immediate consequence of exploiting this vulnerability is a denial of service condition, as accessing memory outside valid bounds typically results in segmentation faults or crashes within the host environment. However, beyond availability impacts, out-of-bounds reads pose significant confidentiality risks by potentially leaking sensitive data stored adjacent to the intended buffer in heap memory. Such information disclosure could expose cryptographic keys, session tokens, or other proprietary application state depending on what resides in the surrounding memory space at runtime. The vulnerability affects all platforms running the specified version of walrus, indicating a systemic issue within the core logic rather than platform-specific implementation details.
This type of flaw is classically categorized under CWE-190 Integer Overflow or Wraparound and often intersects with CWE-787 Out-of-bounds Read when it leads to unauthorized memory access. In terms of adversarial tactics, this vulnerability aligns with ATT&CK techniques related to execution via web-based technologies and potential data exfiltration through side-channel effects if the read operation is controlled precisely enough to infer memory contents. The attack vector requires a remote attacker to deliver malicious WebAssembly content, which may be embedded in HTML pages or delivered via API calls depending on how walrus is integrated into the target application architecture. Defenders must recognize that even sandboxed environments like WebAssembly runtimes are susceptible to low-level implementation errors if input validation and arithmetic operations are not handled with sufficient rigor against edge cases involving maximum integer values.
Mitigation strategies should prioritize immediate patching of the affected walrus version, specifically updating beyond commit ff3bf5ff5c4878f8e5572c9593d303f6bc997443 where this issue has been addressed. Developers integrating walrus into their applications should ensure that dependency management systems are configured to pull the latest secure releases automatically or manually verify version compliance during deployment pipelines. For organizations unable to patch immediately, implementing strict input validation on WebAssembly modules before they reach the runtime layer can provide a secondary defense mechanism. This includes verifying module sizes and memory requirements against expected limits prior to initialization attempts. Additionally, enabling heap sanitizers such as AddressSanitizer in development environments helps detect these types of out-of-bounds accesses early in the software lifecycle rather than allowing them to persist into production deployments where they pose active exploitation risks.