CVE-2026-37555: libsndfile Buffer Overflow Vulnerability

CVE-2026-37555 Overview

An integer overflow vulnerability has been discovered in libsndfile 1.2.2 within the IMA ADPCM codec. This vulnerability exists due to an incomplete fix for CVE-2022-33065, where the AIFF code path was properly patched with a (sf_count_t) cast at line 241, but the WAV code path (line 235) and close path (line 167) remained vulnerable to integer overflow conditions.

When processing maliciously crafted WAV files, the multiplication of samplesperblock (int) and blocks (int) can exceed INT_MAX, causing the 32-bit multiplication to overflow before being assigned to sf.frames (sf_count_t/int64). With attacker-controlled values such as samplesperblock=50000 and blocks=50000, the product of 2,500,000,000 overflows to -1,794,967,296, resulting in an incorrect frame count that can lead to heap buffer overflow or denial of service conditions.

Critical Impact

Attackers can craft malicious WAV files to trigger integer overflow, potentially causing heap buffer overflow or denial of service in applications processing audio files with libsndfile.

Affected Products

• libsndfile 1.2.2
• Applications using libsndfile for WAV/IMA ADPCM audio processing
• Audio processing pipelines and media conversion tools utilizing the vulnerable library

Discovery Timeline

• 2026-04-29 - CVE CVE-2026-37555 published to NVD
• 2026-04-29 - Last updated in NVD database

Technical Details for CVE-2026-37555

Vulnerability Analysis

This vulnerability represents a classic integer overflow condition (CWE-190) that occurs during audio file processing. The root issue lies in how libsndfile calculates memory allocation sizes and frame counts when parsing IMA ADPCM encoded WAV files.

The vulnerability is particularly dangerous because both samplesperblock and blocks values are read directly from the WAV file header, making them fully attacker-controlled. When these values are multiplied together using 32-bit integer arithmetic, the result overflows before being assigned to the 64-bit sf.frames variable. This incorrect frame count subsequently affects memory allocation calculations, leading to undersized buffers that can be overflowed during audio data processing.

The incomplete nature of the previous fix for CVE-2022-33065 highlights the importance of comprehensive patch validation across all code paths that handle similar operations.

Root Cause

The root cause is the use of 32-bit integer multiplication for values that can exceed INT_MAX when multiplied together. While the AIFF code path was fixed with an explicit (sf_count_t) cast to promote the operands to 64-bit before multiplication, the WAV code path and close path were overlooked during the original patch implementation.

The vulnerable pattern involves:

1. Reading samplesperblock and blocks from the file header as 32-bit integers
2. Multiplying these values using 32-bit arithmetic
3. Assigning the overflowed result to a 64-bit variable (sf.frames)

Attack Vector

The attack vector requires an attacker to craft a malicious WAV file with specifically chosen header values that will trigger the integer overflow. The attacker must:

1. Create a WAV file with IMA ADPCM encoding
2. Set samplesperblock and blocks header values such that their product exceeds INT_MAX (2,147,483,647)
3. Deliver the malicious file to a victim application that processes it using libsndfile

This can be exploited remotely if applications accept WAV files from untrusted sources, such as media converters, audio processing pipelines, or web applications that handle user-uploaded audio content.

 	/**
	*	to avoid having to branch when pulling apart the nibbles.
 	*/
 	count = ((samplesperblock - 2) | 7) + 2 ;
-	pimasize = sizeof (IMA_ADPCM_PRIVATE) + psf->sf.channels * (blockalign + samplesperblock + sizeof(short) * count) ;
+	pimasize = sizeof (IMA_ADPCM_PRIVATE) + psf->sf.channels * (blockalign + samplesperblock + sizeof (short) * count) ;
 
 	if (! (pima = calloc (1, pimasize)))
 		return SFE_MALLOC_FAILED ;

Source: GitHub Commit Details

Detection Methods for CVE-2026-37555

Indicators of Compromise

• Unusual WAV file headers containing abnormally large samplesperblock or blocks values
• Application crashes or memory corruption errors when processing WAV files
• Unexpected negative values in audio frame count calculations during file processing
• Memory allocation failures or heap corruption detected by memory sanitizers

Detection Strategies

• Implement input validation to check that samplesperblock * blocks does not exceed safe integer bounds before processing
• Deploy memory sanitizers (ASan, MSan) in development and testing environments to detect heap buffer overflows
• Monitor application logs for crashes related to audio file processing, particularly with IMA ADPCM encoded WAV files
• Use file inspection tools to flag WAV files with suspicious header values before processing

Monitoring Recommendations

• Enable crash reporting and analysis for applications using libsndfile to identify potential exploitation attempts
• Monitor system logs for repeated application crashes or segmentation faults during audio processing operations
• Implement file upload scanning in web applications to validate WAV file header values before processing
• Track memory usage anomalies in audio processing services that may indicate exploitation attempts

How to Mitigate CVE-2026-37555

Immediate Actions Required

• Upgrade libsndfile to a patched version that addresses this integer overflow vulnerability
• Review and audit applications that process untrusted WAV files using libsndfile
• Implement input validation at the application level to reject WAV files with suspiciously large header values
• Consider sandboxing audio processing operations to limit the impact of potential exploitation

Patch Information

The libsndfile development team has addressed this vulnerability in commit 9a829113c88a51e57c1e46473e90609e4b7df151. The fix applies proper type casting to prevent integer overflow during the multiplication operation. Organizations should update to the latest version of libsndfile that includes this fix.

For detailed patch information, refer to the GitHub Commit Details and the GitHub Issue Discussion.

Workarounds

• Validate WAV file headers before processing, rejecting files where samplesperblock * blocks would exceed INT_MAX
• Implement file size limits for uploaded audio files to reduce the attack surface
• Use sandboxed or containerized environments for audio file processing to contain potential exploitation
• Consider using alternative audio processing libraries until the patch can be applied

# Configuration example - Input validation script for WAV files
# Check samplesperblock and blocks values before processing
# Reject files where the product exceeds INT_MAX (2147483647)

# Example validation check (pseudo-code):
# if (samplesperblock * blocks > 2147483647) then reject file
# Apply this validation before passing files to libsndfile