CVE-2026-54059

A flaw was found in Pillow, a Python imaging library. A remote attacker could exploit this vulnerability by providing specially crafted PCF font data. This data, when processed, can lead to excessive memory allocation because the library does not properly check for decompression bombs. The primary consequence is a Denial of Service (DoS), which could make the affected system or application unavailable.

A flaw was found in the Python Pillow library. The PcfFontFile._load_bitmaps() method reads glyph dimensions from the PCF METRICS section and passes them directly to Image.frombytes() without calling Image._decompression_bomb_check(). This allows crafted PCF font data to cause excessive memory allocation, leading to a denial of service condition. An attacker could exploit this by providing a specially crafted PCF font file to an application that uses Pillow's font loading functionality.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Do not load PCF fonts from untrusted sources. If PCF font loading is required, validate font file dimensions before passing them to Pillow, or upgrade to Pillow 12.3.0 or later which includes the fix for this vulnerability.