CVE-2025-54957: Dolby UDC Buffer Overflow Vulnerability

CVE-2025-54957 Overview

An integer overflow vulnerability has been discovered in Dolby UDC (Universal Decoder Core) versions 4.5 through 4.13. The flaw exists in the DD+ (Dolby Digital Plus) decoder process and can be triggered when processing malformed DD+ bitstreams. When Evolution data is parsed by the evo_priv.c component, the decoder writes data into a buffer where the length calculation can overflow due to an integer wraparound. This causes the allocated buffer to be undersized, rendering the subsequent out-of-bounds check ineffective and ultimately resulting in an out-of-bounds write condition.

This vulnerability is particularly concerning as it was analyzed by Google Project Zero in the context of 0-click attack chains on mobile devices, suggesting potential for remote exploitation without user interaction.

Critical Impact

Successful exploitation of this integer overflow vulnerability can lead to arbitrary code execution, memory corruption, or denial of service when a victim processes a maliciously crafted DD+ audio stream. The 0-click nature of the attack vector makes this especially dangerous.

Affected Products

• Dolby UDC versions 4.5 through 4.13
• Devices and software utilizing the Dolby DD+ decoder library
• Systems processing DD+ audio bitstreams (including mobile devices)

Discovery Timeline

• 2025-10-14 - Dolby releases security advisory
• 2025-10-20 - CVE-2025-54957 published to NVD
• 2026-01-15 - Last updated in NVD database

Technical Details for CVE-2025-54957

Vulnerability Analysis

This vulnerability is classified as CWE-190 (Integer Overflow or Wraparound). The core issue resides in the evo_priv.c source file within the Dolby UDC library, which handles Evolution data parsing from DD+ bitstreams.

During normal operation, the decoder calculates the required buffer size for storing Evolution data. However, when processing a maliciously crafted DD+ bitstream containing oversized or manipulated Evolution data fields, the length calculation can wrap around due to integer overflow. This wraparound causes the allocated buffer to be significantly smaller than required.

The vulnerability is network-accessible, as DD+ audio streams can be delivered via streaming services, media files, or other network-based content delivery mechanisms. The attack requires no privileges and no user interaction, making it suitable for 0-click exploitation scenarios.

Root Cause

The root cause is an unsafe integer arithmetic operation in the buffer length calculation within evo_priv.c. When Evolution data size values from the DD+ bitstream are used in multiplication or addition operations without proper bounds checking, the result can exceed the maximum value representable by the integer type, causing it to wrap around to a small positive number. This small value is then used to allocate a buffer that is insufficient to hold the actual data being written, bypassing the out-of-bounds safety checks that follow.

Attack Vector

The attack vector involves delivering a specially crafted DD+ audio bitstream to a vulnerable system. This can be accomplished through various means:

1. Media Playback: Embedding malicious DD+ audio in video files (MP4, MKV, etc.) that are played by the victim
2. Streaming Services: Injecting malicious audio streams through compromised or malicious streaming sources
3. 0-Click Attacks: Delivering the malicious bitstream via messaging apps or other communication channels that automatically process audio content

The vulnerability is exploited when the DD+ decoder processes Evolution data fields that have been crafted to trigger the integer overflow condition. Once the undersized buffer is allocated, subsequent write operations corrupt adjacent memory regions, potentially enabling arbitrary code execution.

The vulnerability mechanism involves manipulating Evolution data fields in the DD+ bitstream to cause integer wraparound during buffer size calculation. For technical details on the exploitation methodology, refer to the Google Project Zero Pixel 0-Click Analysis and the Chromium Project Zero Issue #428075495.

Detection Methods for CVE-2025-54957

Indicators of Compromise

• Unexpected crashes or segmentation faults in audio decoder processes
• Abnormal memory allocation patterns in processes handling DD+ audio streams
• Presence of DD+ audio files with unusually large or malformed Evolution data fields
• Core dumps or crash reports indicating memory corruption in evo_priv.c or related Dolby UDC components

Detection Strategies

• Monitor for crashes in media playback or audio processing services that handle DD+ content
• Implement file integrity monitoring for Dolby UDC library files to detect unauthorized modifications
• Deploy endpoint detection rules that identify unusual memory operations during audio stream processing
• Analyze incoming media files for anomalous DD+ bitstream structures before processing

Monitoring Recommendations

• Enable crash reporting and centralized logging for applications utilizing Dolby UDC
• Monitor system stability metrics on devices that frequently process DD+ audio content
• Implement network-level inspection for suspicious media file downloads or streaming content
• Track version information of Dolby UDC libraries across endpoints to identify vulnerable installations

How to Mitigate CVE-2025-54957

Immediate Actions Required

• Update Dolby UDC to the latest patched version as specified in the vendor advisory
• Restrict processing of DD+ audio streams from untrusted sources where possible
• Implement application sandboxing for media playback applications to contain potential exploitation
• Review and audit systems that process audio content from external or untrusted sources

Patch Information

Dolby has released a security advisory addressing this vulnerability. Organizations using Dolby UDC versions 4.5 through 4.13 should obtain the patched version from Dolby. Refer to the Dolby Security Advisory CVE-2025-54957 for detailed patch information and download instructions.

Device manufacturers and software vendors that integrate Dolby UDC should coordinate with Dolby to obtain updated library versions and push updates to end users.

Workarounds

• Disable automatic processing of DD+ audio streams in messaging and communication applications
• Configure media players to reject DD+ content from untrusted sources
• Implement network filtering to block or quarantine suspicious media files until manual review
• Use application isolation or containerization to limit the impact of potential exploitation

# Example: Verify Dolby UDC library version on Linux systems
find /usr -name "*dolby*" -o -name "*udc*" 2>/dev/null | xargs -I {} ls -la {}

# Check for vulnerable library versions in system package manager
dpkg -l | grep -i dolby
rpm -qa | grep -i dolby