node-fontnik is a library that delivers a range of glyphs rendered as SDFs (signed distance fields) in a protocol buffer. Prior to version 0.7.7, a crafted font could trigger a heap out-of-bounds write in RenderSDF (include/mapbox/glyph_foundry_impl.hpp). RenderSDF computed the SDF bitmap allocation size as buffered_width * buffered_height in 32-bit unsigned int. Glyph dimensions are derived from the uploaded font's outline bounding box with no upper bound, so a glyph large enough to make that product exceed 2³² wrapped to a small value. The buffer was then under-allocated while the render loop still wrote one byte per pixel, corrupting the heap (CWE-190 → CWE-787) and crashing the process. A 680-byte font is enough to drive FreeType to a 65536×65536 buffered glyph, wrapping the size to 0. This issue has been patched in version 0.7.7.
Metrics
Affected Vendors & Products
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Advisories
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Fixes
Solution
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Workaround
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References
History
Wed, 11 Nov 2026 03:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | node-fontnik is a library that delivers a range of glyphs rendered as SDFs (signed distance fields) in a protocol buffer. Prior to version 0.7.7, a crafted font could trigger a heap out-of-bounds write in RenderSDF (include/mapbox/glyph_foundry_impl.hpp). RenderSDF computed the SDF bitmap allocation size as buffered_width * buffered_height in 32-bit unsigned int. Glyph dimensions are derived from the uploaded font's outline bounding box with no upper bound, so a glyph large enough to make that product exceed 2³² wrapped to a small value. The buffer was then under-allocated while the render loop still wrote one byte per pixel, corrupting the heap (CWE-190 → CWE-787) and crashing the process. A 680-byte font is enough to drive FreeType to a 65536×65536 buffered glyph, wrapping the size to 0. This issue has been patched in version 0.7.7. | |
| Title | node-fontnik: integer-overflow heap out-of-bounds write in RenderSDF | |
| Weaknesses | CWE-190 CWE-787 |
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cvssV3_1
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Projects
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-11-11T02:40:47.419Z
Reserved: 2026-07-17T14:47:08.031Z
Link: CVE-2026-63660
Vulnrichment
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NVD
Status : Received
Published: 2026-11-11T03:16:52.367
Modified: 2026-11-11T03:16:52.367
Link: CVE-2026-63660
Redhat
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OpenCVE Enrichment
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