CVE-2026-80335 in Bootloader
Summary
by MITRE • 11/04/2026
In the bootloader download module, there is a possible out-of-bounds write due to a failure to reset a global offset variable during firmware update sessions. This could lead to heap memory corruption, system crash, or potential arbitrary code execution with no additional execution privileges needed.
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Analysis
by VulDB Data Team • 11/04/2026
The vulnerability resides within the bootloader download module of the embedded system's firmware update mechanism, specifically involving improper handling of state variables during multi-session updates. The core technical flaw is a failure to reset a global offset variable when initiating or transitioning between firmware update sessions. In typical embedded systems, the bootloader manages memory allocation for incoming firmware images by tracking byte offsets into heap-allocated buffers. When an update session concludes without properly resetting this global counter, subsequent operations may continue writing data from where the previous session left off rather than starting at the beginning of the allocated buffer. This logic error results in a write operation that exceeds the bounds of the intended memory region, leading to out-of-bounds heap corruption.
The operational impact of this vulnerability is severe due to its potential for arbitrary code execution without requiring additional privileges. Since the bootloader often runs with high-level system access before the operating system fully initializes, an attacker who can trigger a malformed or repeated firmware update sequence could exploit this memory corruption to overwrite critical control data on the heap. This includes function pointers, return addresses, or other metadata that dictates program flow. By carefully crafting the input payload during the download process, an adversary can manipulate these overwritten values to redirect execution to malicious shellcode placed in adjacent writable memory regions. The lack of required additional privileges makes this particularly dangerous as it lowers the barrier for exploitation significantly.
From a classification perspective, this vulnerability aligns with CWE-787: Out-of-bounds Write, which describes writing data outside the boundaries of allocated memory. Furthermore, given that the exploit involves manipulating heap structures to achieve code execution, it maps closely to ATT&CK technique T1203: Exploitation for Defense Evasion or potentially T1059 if considered part of a broader command and control setup during boot processes. The specific context of firmware updates also relates to supply chain attack vectors where integrity checks might be bypassed through memory corruption rather than cryptographic failure, highlighting the importance of robust state management in security-critical components like bootloaders.
Mitigation strategies must focus on rigorous input validation and strict state machine enforcement within the bootloader codebase. Developers should ensure that all global variables related to buffer offsets are explicitly initialized or reset at the start of every new firmware download session. Implementing bounds checking for every write operation into heap-allocated buffers is essential, even if internal trust assumptions suggest such checks are unnecessary. Additionally, enabling compiler-based security features such as stack canaries and Address Space Layout Randomization (ASLR) where supported by the hardware architecture can mitigate exploitation success rates. Regular static analysis of embedded C code using tools configured to detect out-of-bounds writes will help identify similar logic errors before deployment. Finally, implementing secure boot chains with cryptographic verification ensures that even if memory corruption occurs, unsigned or tampered code cannot be executed during the critical early stages of system initialization.