CVE-2026-51270 in ESP32-audioI2S
Summary
by MITRE • 07/28/2026
schreibfaul1 ESP32-audioI2S 3.4.5 has a heap-based buffer overflow vulnerability in the htmlToUTF8() HTML entity decoding function. The function parses attacker-controlled malicious HTML entities and uses memmove and memcpy to rearrange string content without validating buffer remaining size and boundary limits. Crafted oversized HTML entity strings can trigger heap out-of-bounds write, allowing remote code execution, memory information leakage, service crash or privilege escalation.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 07/28/2026
The schreibfaul1 ESP32-audioI2S library version 3.4.5 contains a critical heap-based buffer overflow vulnerability within its htmlToUTF8() function that processes HTML entity decoding operations. This vulnerability arises from insufficient input validation and boundary checking during string manipulation operations, creating a significant security risk for embedded audio applications running on ESP32 microcontrollers. The flaw specifically manifests when the function handles attacker-controlled HTML entities that undergo parsing and subsequent memory copying operations.
The technical implementation of this vulnerability stems from improper buffer management within the htmlToUTF8() function where memmove and memcpy operations are performed without adequate validation of available buffer space or boundary limits. When malicious HTML entity strings exceed expected size parameters, these memory manipulation functions can overwrite adjacent heap memory regions, leading to unpredictable behavior and potential exploitation. The vulnerability operates at the heap level, making it particularly dangerous as it can corrupt critical program data structures and memory management metadata.
This buffer overflow presents severe operational impacts including remote code execution capabilities that could allow attackers to gain control over affected devices running the vulnerable library. The vulnerability also enables memory information leakage through heap corruption, potentially exposing sensitive data or system internals. Additionally, successful exploitation can cause service crashes and denial of service conditions, while in some scenarios may facilitate privilege escalation attacks on systems with elevated permissions. The nature of the vulnerability makes it particularly concerning for embedded audio applications where device compromise could lead to unauthorized media access or manipulation.
From a cybersecurity perspective, this vulnerability maps to CWE-129, which specifically addresses improper validation of buffer sizes and boundary checks in memory operations. The attack surface aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where remote code execution could enable adversaries to establish persistent access through malicious HTML content injection. Organizations should prioritize immediate patching or mitigation strategies including input validation restrictions, heap memory sanitization, and runtime protections to prevent exploitation. The vulnerability represents a critical security gap in embedded audio processing libraries that requires urgent attention from both developers and system administrators managing affected ESP32-based audio applications.
The remediation approach should focus on implementing proper buffer size validation before memory operations, utilizing safe string manipulation functions with built-in boundary checking, and conducting comprehensive input sanitization for all HTML entity processing. Additionally, employing heap memory protection mechanisms such as stack canaries or address space layout randomization could provide additional defense layers against exploitation attempts. Regular security auditing of embedded library dependencies remains essential to identify similar vulnerabilities in other third-party components used within IoT and embedded audio systems.