CVE-2026-66039: ffmpeg Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-66039 is a high (CVSS 8.8) Heap-based Buffer Overflow vulnerability in ffmpeg. EPSS estimates a 0.31% chance of exploitation in the next 30 days, higher than 22% of scored vulnerabilities.

Timeline

1. 24-07-2026
   PublishedVulnerability first disclosed.
2. 29-07-2026
   Last modifiedVulnerability information updated.

Description

FFmpeg through 8.1.2, fixed in commit aafb5c6, contains a signed integer overflow vulnerability in the MACE6 audio decoder that allows attackers to corrupt heap memory by supplying a crafted CAF file with a malicious bytes_per_packet value. Attackers can craft a CAF file with oversized bytes_per_packet and frames_per_packet values in the desc chunk to trigger an integer overflow in mace_decode_frame() during output sample count computation, resulting in an undersized buffer allocation and heap out-of-bounds write that could enable code execution.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
• CWE-190Integer Overflow or WraparoundThe product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.