CVE-2026-25646: libpng Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-25646 is a high (CVSS 8.3) Heap-based Buffer Overflow vulnerability in libpng. EPSS estimates a 0.72% chance of exploitation in the next 30 days, higher than 53% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 10-02-2026
   PublishedVulnerability first disclosed.
2. 01-09-2026
   Last modifiedVulnerability information updated.

Description

LIBPNG is a reference library for use in applications that read, create, and manipulate PNG (Portable Network Graphics) raster image files. Prior to 1.6.55, an out-of-bounds read vulnerability exists in the png_set_quantize() API function. When the function is called with no histogram and the number of colors in the palette is more than twice the maximum supported by the user's display, certain palettes will cause the function to enter into an infinite loop that reads past the end of an internal heap-allocated buffer. The images that trigger this vulnerability are valid per the PNG specification. This vulnerability is fixed in 1.6.55.

• 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-126Buffer Over-readThe product reads from a buffer using buffer access mechanisms such as indexes or pointers that reference memory locations after the targeted buffer.
• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.