A heap bufferflow in pcfReadFont() due to missing glyph bounds checking in libXfont2 before 2.0.8 allows attackers authenticated as X client to execute code within the X server.

A flaw was found in libXfont2. A specially crafted PCF (Portable Compiled Format) font file, when processed by libXfont2, can lead to a buffer overflow. This occurs because the font parsing process does not properly validate the size of a bitmap buffer against the glyph metrics provided in the malicious font file. An attacker could exploit this vulnerability by providing a malicious font, potentially leading to arbitrary code execution or a denial of service.

This is an Important flaw in libXfont2, affecting Red Hat Enterprise Linux. A heap buffer overflow during PCF font file parsing can lead to arbitrary code execution or denial of service. Exploitation requires processing a specially crafted font file, but does not necessitate rendering. Red Hat Enterprise Linux 10 Under investigation libXfont2 Red Hat Enterprise Linux 7 Under investigation libXfont2 Red Hat Enterprise Linux 8 Under investigation libXfont2 Red Hat Enterprise Linux 9 Under investigation libXfont2 https://www.cve.org/CVERecord?id=CVE-2026-56002 https://nvd.nist.gov/vuln/detail/CVE-2026-56002