High [CVE-2026-56001] BitmapScaleBitmaps Integer Overflow Heap Buffer Overflow

A heap buffer overflow in BitmapScaleBitmaps in libXfont2 before 2.0.8 due to an overflowing 32bit size could be used by attackers able to access the X Server to execute code within the X server cont A flaw was found in libXfont2. In the BitmapScaleBitmaps() function, an integer overflow can occur when calculating the memory needed for font glyphs.

This overflow leads to a heap buffer overflow, where a smaller-than-required memory buffer is allocated. A local attacker can exploit this by loading a specially crafted PCF font, potentially leading to arbitrary code execution or a denial of service.

This flaw in libXfont2 is rated as Important. A local attacker could exploit an integer overflow in the `BitmapScaleBitmaps()` function, leading to a heap buffer overflow and potential arbitrary code execution or denial of service.

This vulnerability requires the processing of a specially crafted PCF font, typically through an X server or an application configured to load untrusted font files. Red Hat severity: Important — CVSS 7.3 (CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H).

Affected products named by the advisory: Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 7 Extended Lifecycle Support; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On; and 8 more.