Buffer Overflow Vulnerability in MCUboot Affects Mynewt Applications

CVE-2026-16671

What is CVE-2026-16671?

A buffer overflow vulnerability arises in the split_image_check() function of MCUboot when handling certain digest sizes. The function declares a fixed buffer for tracking SHA-256 hashes but mistakenly allows larger sizes such as SHA-512 or SHA-384 to be copied into it. This overflow can lead to corruption of the bootloader's stack during the boot process, affecting the stability of Mynewt applications. The vulnerability necessitates specific build configurations and does not affect the default SHA-256 builds. A patch is available to resolve the issue by correctly sizing the buffer.

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