FFmpeg <=8.1.2 PNG/APNG Encoder OOB Write via eXIf Chunk
CVE-2026-66040 Published on July 24, 2026
FFmpeg Heap Out-of-Bounds Write via PNG/APNG eXIf Encoder
FFmpeg through 8.1.2, fixed in commit b506faf, contains a heap out-of-bounds write vulnerability in the native PNG and APNG encoders that allows remote attackers to corrupt heap memory by supplying a crafted PNG image with a malicious eXIf chunk. Attackers can craft an eXIf chunk where multiple IFD entries reference the same large value payload, causing canonical serialization to expand the output far beyond the undersized allocation estimated by add_exif_profile_size(), resulting in png_write_chunk() writing tens of thousands of bytes past the buffer boundary, leading to deterministic heap corruption, process crash, and potentially arbitrary code execution.
Vulnerability Analysis
CVE-2026-66040 is exploitable with network access. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Heap-based Buffer Overflow
A 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().
Products Associated with CVE-2026-66040
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Affected Versions
FFmpeg:- Before and including 8.1.2 is affected.
- Version b506fafec9a19fcbc2be5271875fd4a63d6615bc is unaffected.