CVE-2026-51267 in ESP32-audioI2S
Summary
by MITRE • 07/28/2026
schreibfaul1 ESP32-audioI2S 3.4.5 has a heap-based buffer overflow vulnerability in the URL path concatenation and encoding module. The application splices untrusted extension path and attacker-controlled query string into a path buffer, then invokes urlencode without validating the final string length. Remote attackers can construct an oversized malicious URL path and query string to trigger out-of-bounds heap write, resulting in arbitrary code execution, information disclosure, service crash, or privilege escalation.
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Analysis
by VulDB Data Team • 07/28/2026
The schreibfaul1 ESP32-audioI2S version 3.4.5 vulnerability represents a critical heap-based buffer overflow that emerges from improper handling of URL path concatenation and encoding operations. This flaw exists within the application's core processing pipeline where untrusted extension paths and attacker-controlled query strings are concatenated into a fixed-size path buffer without adequate length validation. The vulnerability manifests when the system invokes urlencode function without first verifying whether the resulting string would exceed the allocated buffer boundaries, creating a condition where memory corruption becomes possible through carefully crafted malicious inputs. The affected component specifically processes audio streaming URLs where the application expects to handle various media source identifiers and parameters that are typically provided by external users or systems. This type of vulnerability is particularly dangerous in embedded IoT environments like ESP32 devices where resource constraints limit defensive capabilities and where the attack surface includes network-accessible services.
The technical exploitation of this buffer overflow occurs through precise manipulation of URL components that are then processed through the vulnerable concatenation logic. When an attacker constructs a malicious URL with an oversized extension path combined with a lengthy query string, the system performs no bounds checking before executing the urlencode operation. This creates an out-of-bounds heap write condition where the application attempts to write data beyond the allocated memory space for the path buffer. The heap corruption can result in multiple security outcomes including arbitrary code execution through controlled memory overwrite, information disclosure via memory content exposure, service crash due to memory corruption, or even privilege escalation if the vulnerable component operates with elevated system permissions. The vulnerability maps directly to CWE-121 Heap-based Buffer Overflow which specifically addresses buffer overflows occurring in heap memory regions. From an attack perspective, this flaw aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where malicious code execution could be achieved through controlled buffer overflow exploitation.
The operational impact of this vulnerability extends beyond simple denial-of-service conditions to encompass complete system compromise in environments where ESP32-audioI2S is deployed as a streaming media server or audio processing node. In IoT deployments, these devices often serve as edge computing nodes that handle sensitive audio data streams and may be integrated into larger network infrastructures where unauthorized code execution could lead to broader network infiltration. The vulnerability affects systems that process external URL inputs for audio content delivery, including smart home audio systems, industrial audio streaming solutions, or embedded multimedia applications. Organizations using this software in production environments face potential exposure to attackers who can leverage the buffer overflow to gain persistent access to devices, extract sensitive information from memory, or disrupt service availability. The remote nature of the attack vector means that exploitation can occur without physical access to the device, making it particularly concerning for network-connected embedded systems where traditional physical security measures are insufficient.
Mitigation strategies for this vulnerability require immediate implementation of input validation controls and buffer size enforcement mechanisms. The most effective approach involves implementing strict bounds checking before any URL concatenation operations, ensuring that the final encoded string length never exceeds the allocated buffer capacity. Developers should implement proper memory management practices including dynamic buffer allocation based on actual input requirements or fixed-size buffers with comprehensive overflow detection. Input sanitization measures must be applied to all external URL components including path extensions and query parameters, with validation routines that reject oversized inputs before processing begins. Additionally, implementing stack canaries, address space layout randomization, and other memory protection mechanisms can help detect and prevent exploitation attempts. Organizations should also consider applying firmware updates or patches as soon as available from the software vendor to remediate this vulnerability. Regular security assessments of embedded systems and network monitoring for suspicious URL patterns can provide early detection of potential exploitation attempts, while maintaining detailed audit logs of URL processing activities can aid in forensic analysis if compromise occurs. The vulnerability highlights the critical need for proper secure coding practices in embedded environments where memory constraints are typically managed through manual buffer handling rather than automated safety mechanisms.