Out-of-bounds read in libpng png_set_quantize()
CVE-2026-25646 is a high-severity memory-safety flaw in libpng, the reference library for reading and writing PNG images. The vulnerability is in the png_set_quantize() API function (formerly png_set_dither). In affected versions prior to 1.6.55, when png_set_quantize() is invoked without a histogram and the palette contains more than twice the maximum number of colors supported by the caller's display configuration, certain valid PNG palettes can cause the function to enter an infinite loop and read past the end of an internal heap-allocated buffer. The issue is described as an out-of-bounds read / heap buffer overflow condition during palette quantization. Triggering images are valid under the PNG specification, and the flaw reportedly existed since the initial implementation of png_set_quantize().
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Recent activity
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Unknown (listed as a trending CVE for libpng without details in the provided content).
A high-severity libpng vulnerability in png_set_quantize() (aka png_set_dither) that can trigger an infinite loop with out-of-bounds heap reads when processing specially crafted PNGs (palette present without histogram), leading to DoS and potentially information disclosure or arbitrary code execution with heap grooming.
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Every observed campaign linking this CVE to a named adversary.
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Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.