Bug 2512517 (CVE-2026-18497)

Summary: CVE-2026-18497 stb: nothings stb TrueType library: Heap Buffer Overflow via malformed TrueType Font files
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: high    
Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the nothings stb TrueType library, which is used for parsing TrueType font files. A remote attacker could exploit this vulnerability by crafting a malicious TrueType Font (TTF) file. When an application attempts to process this malformed file, a heap buffer overflow occurs in the stbtt__GetGlyphShapeTT() function, leading to an out-of-bounds read. This could result in a denial of service or potentially arbitrary code execution.
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Bug Depends On: 2521843, 2521844, 2521845    
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Description OSIDB Bzimport 2026-08-07 14:41:24 UTC 
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.