CVE-2026-1940: GStreamer Buffer Overflow Vulnerability

CVE-2026-1940 Overview

An incomplete fix for CVE-2024-47778 allows an out-of-bounds read in the gst_wavparse_adtl_chunk() function within GStreamer. The patch added a size validation check lsize + 8 > size, but it does not account for the GST_ROUND_UP_2(lsize) used in the actual offset calculation. When lsize is an odd number, the parser advances more bytes than validated, causing an out-of-bounds read condition.

Critical Impact

This vulnerability enables attackers to potentially read memory beyond buffer boundaries when processing maliciously crafted WAV files, which could lead to information disclosure or application crashes.

Affected Products

• GStreamer multimedia framework (wavparse plugin)
• Linux distributions shipping vulnerable GStreamer versions
• Applications using GStreamer for WAV file processing

Discovery Timeline

• 2026-03-23 - CVE CVE-2026-1940 published to NVD
• 2026-03-24 - Last updated in NVD database

Technical Details for CVE-2026-1940

Vulnerability Analysis

This vulnerability represents an Out-of-Bounds Read (CWE-125) in GStreamer's WAV file parser. The flaw exists due to an incomplete remediation of CVE-2024-47778, where the security patch introduced a boundary validation check that fails to account for byte alignment operations performed during buffer traversal.

The core issue stems from a discrepancy between the validation logic and the actual memory access pattern. While the patch validates that lsize + 8 does not exceed size, the subsequent code uses GST_ROUND_UP_2(lsize) to calculate the offset for advancing through the buffer. This macro rounds up odd values to the next even number for alignment purposes.

When an attacker provides a WAV file with a carefully chosen odd lsize value, the validation passes, but the parser reads one byte beyond what was validated. This creates a window for out-of-bounds memory access that can result in information leakage or denial of service through application crashes.

Root Cause

The root cause is a logic error in the size validation introduced by the CVE-2024-47778 patch. The validation check lsize + 8 > size does not account for the byte alignment performed by GST_ROUND_UP_2(lsize), which adds an extra byte when lsize is odd. This creates an off-by-one condition that allows reading beyond the validated buffer boundary.

Attack Vector

The vulnerability requires local access and involves processing a maliciously crafted WAV file. An attacker can exploit this flaw by:

1. Creating a specially crafted WAV file with an ADTL (Associated Data List) chunk
2. Setting the lsize field to an odd value that passes the boundary check but causes OOB read after rounding
3. Tricking a user or application into processing the malicious WAV file with GStreamer

The attack does not require special privileges and can be triggered without user interaction beyond opening the malicious file. The vulnerability could potentially be exploited in scenarios where GStreamer automatically processes media files, such as thumbnail generation or media indexing services.

Detection Methods for CVE-2026-1940

Indicators of Compromise

• Unexpected crashes or segmentation faults in GStreamer-based applications when processing WAV files
• Memory access violations reported by system logs during media file processing
• Application core dumps indicating reads from invalid memory addresses in wavparse-related code paths

Detection Strategies

• Monitor for application crashes related to GStreamer or wavparse components
• Implement file integrity monitoring on media processing services
• Deploy memory sanitizer tools in development and testing environments to catch OOB reads
• Review system logs for segmentation faults or memory errors associated with media playback

Monitoring Recommendations

• Enable crash reporting for all applications utilizing GStreamer for audio processing
• Set up alerting for unusual terminations of media processing services
• Monitor memory usage patterns in GStreamer-based applications for anomalies
• Implement file scanning for WAV files with unusual ADTL chunk structures before processing

How to Mitigate CVE-2026-1940

Immediate Actions Required

• Update GStreamer to the latest patched version as indicated in GStreamer Security Advisory SA-2026-0001
• Check distribution-specific security advisories from Red Hat and Debian for available patches
• Audit systems using GStreamer for WAV file processing and prioritize patching
• Consider restricting WAV file processing from untrusted sources until patches are applied

Patch Information

Security patches are available through the official GStreamer project and major Linux distributions. Refer to the GStreamer Security Advisory SA-2026-0001 for detailed patch information and the corrected validation logic. Additional tracking is available via Red Hat Bug Report #2436932 and GitLab Issue #4854.

Workarounds

• Disable or remove the wavparse plugin if WAV file processing is not required
• Implement application-level input validation to reject WAV files with suspicious ADTL chunk sizes
• Use sandboxing or containerization to limit the impact of potential exploitation
• Restrict file processing to trusted sources only until the patch can be applied

# Configuration example
# Check installed GStreamer version
gst-inspect-1.0 --version

# List installed wavparse plugin details
gst-inspect-1.0 wavparse

# Optionally blacklist wavparse plugin until patched (requires restart of applications)
# Create blacklist file to disable vulnerable plugin
echo "wavparse" > ~/.config/gstreamer-1.0/plugin-blacklist.txt