CVE-2026-51275 Overview
CVE-2026-51275 is a heap-based buffer overflow [CWE-122] in the schreibfaul1 ESP32-audioI2S library version 3.4.5. The flaw resides in the ID3v2 APIC frame parsing routine inside audiolib. An attacker who supplies a crafted MP3 file can trigger an out-of-bounds heap write. Successful exploitation permits arbitrary code execution on the ESP32 device or a denial-of-service crash. The vulnerability is reachable over the network because the library streams remote audio, requiring only that a user or automated process loads the malicious file.
Critical Impact
Remote attackers can execute arbitrary code on ESP32 devices running vulnerable firmware by delivering a malformed MP3, compromising IoT endpoints and connected audio systems.
Affected Products
- schreibfaul1 ESP32-audioI2S version 3.4.5
- ESP32 firmware images that embed the vulnerable audiolib component
- Downstream IoT audio projects that link against the affected release
Discovery Timeline
- 2026-07-28 - CVE-2026-51275 published to the National Vulnerability Database (NVD)
- 2026-07-28 - Public advisory posted to the GitHub CVE-2026-51275 Advisory
- 2026-07-28 - Last updated in NVD database
Technical Details for CVE-2026-51275
Vulnerability Analysis
The defect lives in the ID3v2 metadata parser that handles Attached Picture (APIC) frames within MP3 headers. When the parser reads the frame size field declared by the file, it does not validate that value against the destination heap buffer size. The parser then copies the frame payload using the attacker-controlled length, producing an out-of-bounds write on the heap. Because ESP32 firmware typically executes without modern mitigations such as ASLR or non-executable heap regions, memory corruption on this platform frequently translates to reliable code execution. Attackers can pivot from the corrupted heap chunk into control-flow hijacking or crash the audio task to disrupt device functionality.
Root Cause
The root cause is missing length validation on the APIC frame size field during ID3v2 parsing. The parser trusts the size declared inside the MP3 metadata and writes the full payload into a fixed-size heap allocation. See the upstream source at ESP32-audioI2S Audio.cpp for the affected code path.
Attack Vector
Exploitation requires an ESP32 device to load a crafted MP3 supplied by the attacker. Delivery vectors include internet radio streams, HTTP audio endpoints, SD card content, and Bluetooth or Wi-Fi file transfers consumed by the audio pipeline. User interaction is limited to initiating playback, which many devices perform automatically on stream connect. No authentication is required against the audio library itself.
No verified proof-of-concept code is publicly available. Refer to the GitHub CVE-2026-51275 Advisory for technical detail.
Detection Methods for CVE-2026-51275
Indicators of Compromise
- Unexpected reboots, watchdog resets, or crash logs originating from the audio task on ESP32 devices
- MP3 files with APIC frame size fields that exceed the declared ID3v2 tag length
- Outbound audio stream connections to unknown hosts followed by device instability
- Firmware serial console output showing heap corruption or LoadProhibited exceptions during playback
Detection Strategies
- Perform static analysis on firmware images to identify the vulnerable audiolib version 3.4.5
- Inspect ingested MP3 files at network egress points, validating ID3v2 APIC frame size against total tag size
- Correlate crash telemetry from ESP32 fleets with recent audio URL changes or firmware updates
Monitoring Recommendations
- Log and alert on ESP32 crash dumps, watchdog resets, and abnormal task terminations
- Monitor HTTP and HTTPS audio stream sources referenced by device configurations for reputation and integrity changes
- Track firmware inventory to flag any deployment carrying schreibfaul1 ESP32-audioI2S 3.4.5
How to Mitigate CVE-2026-51275
Immediate Actions Required
- Identify all ESP32 devices and firmware builds that link schreibfaul1 ESP32-audioI2S 3.4.5
- Restrict audio playback to trusted, allowlisted stream sources until a fix is deployed
- Disable ID3v2 metadata parsing in device configurations where the option is exposed
- Rebuild and redeploy firmware once an upstream patch is published in the ESP32-audioI2S repository
Patch Information
No fixed version is referenced in the NVD entry at publication time. Monitor the upstream schreibfaul1/ESP32-audioI2S repository for a release beyond 3.4.5 that adds length validation to the APIC frame parser, then rebuild dependent firmware and roll out over-the-air updates.
Workarounds
- Filter or strip ID3v2 APIC frames from MP3 content at a proxy or transcoder before the file reaches the device
- Enforce network egress controls so ESP32 devices only reach vetted audio endpoints
- Apply a local patch that clamps the parsed APIC size to the remaining tag length and the allocated buffer size
# Configuration example: restrict ESP32 audio egress at the network boundary
iptables -A FORWARD -s 192.0.2.0/24 -p tcp --dport 80 -d trusted-stream.example.net -j ACCEPT
iptables -A FORWARD -s 192.0.2.0/24 -p tcp --dport 443 -d trusted-stream.example.net -j ACCEPT
iptables -A FORWARD -s 192.0.2.0/24 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
