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Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process. A heap-buffer-overflow vulnerability exists in the nothings stb TrueType library, up to version 1.26, that is used for parsing TrueType font files. The vulnerability exists in the stbtt__GetGlyphShapeTT() function within the nothings stb_truetype.h library when parsing malformed TTF (TrueType Font) files. The vulnerability resides in the glyph data parsing path. An attacker can craft a malformed TTF file with an inflated endPtsOfContours value and truncate the remaining glyph data. When an application utilizing stb_truetype.h (such as various game engines or graphics software) attempts to load, bake, or render this malformed font via stbtt_GetGlyphShape(), the parser will attempt to read past the end of the glyph data buffer, triggering the out-of-bounds read.
Neither the CVE https://www.cve.org/CVERecord?id=CVE-2026-18497 nor the linked upstream issue https://github.com/nothings/stb/issues/1905 includes a patch. Given that the stb_truetype library begins with the following prominent warning, // ======================================================================= // // NO SECURITY GUARANTEE -- DO NOT USE THIS ON UNTRUSTED FONT FILES // // This library does no range checking of the offsets found in the file, // meaning an attacker can use it to read arbitrary memory. // // ======================================================================= it’s certain that upstream would not consider this a valid bug. For those reasons, I’m not interested in trying to develop a patch for this, either. Given that there’s no patch and probably never will be one, it doesn’t seem useful to track this downstream. Feel free to reopen this or open a PR if a proposed patch appears, but please understand that stb_truetype is expected to be absolutely riddled with problems like this when used outside of the applications for which it was designed.