CVE-2026-51274 Overview
CVE-2026-51274 is a heap-based buffer overflow [CWE-122] in the schreibfaul1 ESP32-audioI2S library version 3.4.5. The flaw resides in the ID3v2 SYLT (Synchronized Lyrics) parser inside the audiolib component. A remote attacker can trigger the overflow by delivering a crafted MP3 file to a vulnerable device. Successful exploitation can cause a denial of service, disclose memory contents, or lead to arbitrary code execution on the ESP32 microcontroller.
Critical Impact
A single malicious MP3 file processed by the ESP32-audioI2S library can crash the device, leak memory, or execute attacker-controlled code on embedded audio hardware.
Affected Products
- schreibfaul1/ESP32-audioI2S version 3.4.5
- ESP32-based devices and firmware embedding the audiolib MP3 decoder
- Downstream projects consuming the vulnerable ID3v2 SYLT parser in Audio.cpp
Discovery Timeline
- 2026-07-28 - CVE-2026-51274 published to NVD
- 2026-07-28 - Last updated in NVD database
Technical Details for CVE-2026-51274
Vulnerability Analysis
The ESP32-audioI2S library parses ID3v2 metadata tags embedded in MP3 files. The SYLT frame carries synchronized lyric data with timestamps and a text payload. The parser reads the frame size field directly from the file and uses it to drive memory operations without validating the value against the allocated buffer. An attacker controls this frame size by crafting an MP3 file with an oversized SYLT frame header.
Because the ESP32-audioI2S library commonly runs on Internet-connected audio streamers, web radios, and IoT audio endpoints, the attack surface reaches any device that fetches or plays remote MP3 streams. Exploitation requires the user or firmware to load the malicious file, satisfying the user-interaction requirement in the CVSS vector.
Root Cause
The root cause is missing bounds validation on an attacker-controlled length field combined with improper memory access during lyric parsing. The SYLT handler in Audio.cpp trusts the frame size declared in the ID3v2 header and writes lyric data into a heap buffer sized for expected content. When the declared size exceeds the destination buffer, the parser writes past the allocation boundary, corrupting adjacent heap metadata and objects.
Attack Vector
An attacker crafts an MP3 file containing a malformed ID3v2 tag with an oversized or malicious SYLT frame. The file is delivered through any channel the device consumes: HTTP streaming URLs, SD card content, Bluetooth audio sources, or web radio playlists. When the ESP32 firmware invokes the audio decoder on the crafted file, the SYLT parser executes the vulnerable code path. On embedded targets without heap hardening, the resulting corruption can be shaped into control-flow hijack primitives.
No verified public exploit code is available. Technical details are documented in the GitHub CVE Advisory and the affected source is visible in the ESP32-audioI2S Audio.cpp.
Detection Methods for CVE-2026-51274
Indicators of Compromise
- Unexpected ESP32 device reboots, watchdog resets, or crash dumps generated while decoding MP3 content
- MP3 files containing ID3v2 SYLT frames with abnormally large declared frame sizes relative to actual payload
- Outbound requests from ESP32 devices to unfamiliar hosts serving MP3 or streaming radio content
Detection Strategies
- Inspect MP3 files at the network or storage boundary and flag ID3v2 SYLT frames where the declared frame size exceeds a sane maximum for lyric content
- Correlate ESP32 firmware crash telemetry with recent audio playback activity to identify parser-triggered faults
- Monitor firmware image inventories for the vulnerable ESP32-audioI2S 3.4.5 component in build manifests and SBOMs
Monitoring Recommendations
- Capture serial or syslog output from ESP32 fleets to catch heap corruption panics and stack traces referencing the audio decoder
- Log all remote MP3 stream URLs and playlist sources loaded by IoT audio devices for post-incident review
- Track device restart frequency and alert when a device exhibits repeated crashes tied to specific media sources
How to Mitigate CVE-2026-51274
Immediate Actions Required
- Identify all firmware builds that link against schreibfaul1/ESP32-audioI2S version 3.4.5 and mark them for update
- Restrict devices to trusted MP3 sources and disable playback of user-supplied or unauthenticated stream URLs until patched
- Rebuild and reflash firmware once an upstream fix is available in the ESP32-audioI2S repository
Patch Information
No vendor-issued patch or fixed version was referenced in the NVD entry at publication. Monitor the upstream schreibfaul1/ESP32-audioI2S repository for a commit addressing SYLT frame size validation in Audio.cpp. Downstream firmware maintainers should pin to a fixed release once published and issue over-the-air updates.
Workarounds
- Strip or sanitize ID3v2 tags from MP3 content served to ESP32 devices, removing SYLT frames before delivery
- Enforce allowlists of trusted streaming servers and reject arbitrary user-supplied URLs at the firmware or proxy layer
- Disable ID3v2 metadata parsing in downstream forks where lyric display is not required for the product use case
# Configuration example: proxy-side ID3v2 SYLT frame stripping
# Use id3v2 tooling to remove synchronized lyric frames before delivery
id3v2 --delete-frames=SYLT /srv/media/incoming.mp3
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
