VU#987105: The nothings stb TrueType library, up to version 1.26, contains a heap buffer overflow vulnerability
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.
AI Analysis
Technical Summary
CVE-2026-18497 is a heap buffer overflow vulnerability in the nothings stb TrueType library (stb_truetype.h) up to version 1.26. The flaw exists in the stbtt_GetGlyphShape() function during glyph contour parsing, where the function iterates based on the endPtsOfContours value without validating that the points pointer remains within the glyph data buffer bounds. An attacker can craft a malformed TrueType font file with an inflated endPtsOfContours and truncated glyph data, causing the parser to read beyond the allocated heap buffer. This results in out-of-bounds heap reads, potentially leading to application crashes or information disclosure. The maintainer has not yet provided a fix or statement, and users are cautioned about the potential risk.
Potential Impact
Exploitation can cause denial of service through application crashes due to invalid heap memory reads. Additionally, there is potential for information disclosure by reading adjacent heap memory. No known exploits are reported in the wild at this time.
Mitigation Recommendations
No official fix or patch is currently available. The vendor has not responded to coordination attempts and has indicated that security fixes may take significant time. Users should monitor the project's GitHub repository for updates and avoid using the stb TrueType library if this risk is unacceptable. Applying a fix when released is recommended.
VU#987105: The nothings stb TrueType library, up to version 1.26, contains a heap buffer overflow vulnerability
Description
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.
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-18497 is a heap buffer overflow vulnerability in the nothings stb TrueType library (stb_truetype.h) up to version 1.26. The flaw exists in the stbtt_GetGlyphShape() function during glyph contour parsing, where the function iterates based on the endPtsOfContours value without validating that the points pointer remains within the glyph data buffer bounds. An attacker can craft a malformed TrueType font file with an inflated endPtsOfContours and truncated glyph data, causing the parser to read beyond the allocated heap buffer. This results in out-of-bounds heap reads, potentially leading to application crashes or information disclosure. The maintainer has not yet provided a fix or statement, and users are cautioned about the potential risk.
Potential Impact
Exploitation can cause denial of service through application crashes due to invalid heap memory reads. Additionally, there is potential for information disclosure by reading adjacent heap memory. No known exploits are reported in the wild at this time.
Mitigation Recommendations
No official fix or patch is currently available. The vendor has not responded to coordination attempts and has indicated that security fixes may take significant time. Users should monitor the project's GitHub repository for updates and avoid using the stb TrueType library if this risk is unacceptable. Applying a fix when released is recommended.
Technical Details
- Classification
- {"confidence":0.93,"severitySource":"heuristic","classifier":"rss-v2"}
- Article Source
- {"url":"https://kb.cert.org/vuls/id/987105","fetched":true,"fetchedAt":"2026-08-07T14:24:06.371Z","wordCount":557}
Threat ID: 6a75ea86bf8831d5396f0a8f
Added to database: 08/07/2026, 14:24:06 UTC
Last enriched: 08/15/2026, 12:58:48 UTC
Last updated: 09/22/2026, 13:47:43 UTC
Views: 74
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