Local code execution via font subsetter overflow
Published Aug 11, 2026 · Updated Aug 25, 2026
Out-of-bounds write in WPF in Microsoft .NET and Visual Studio allows local users to execute code via crafted fonts. In the TrueType subsetter used by GlyphTypeface.ComputeSubset and XPS font embedding, 16-bit counters can wrap during font-table walks and continue writing past a heap buffer using attacker-controlled counts and offsets from font metadata. Reachability depends on a WPF path that subsets or embeds untrusted fonts, such as document export, PDF generation, or printing, and successful exploitation runs in the current user's context.
Summary
What happened
Out-of-bounds write in WPF in Microsoft .NET and Visual Studio allows local users to execute code via crafted fonts. In the TrueType subsetter used by GlyphTypeface.ComputeSubset and XPS font embedding, 16-bit counters can wrap during font-table walks and continue writing past a heap buffer using attacker-controlled counts and offsets from font metadata. Reachability depends on a WPF path that subsets or embeds untrusted fonts, such as document export, PDF generation, or printing, and successful exploitation runs in the current user's context.
The record
- CVE
- CVE-2026-62871
- Published
- Aug 11, 2026
- Updated
- Aug 25, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-787, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 11, 2026CVE publishedPublication date reported by the CVE source.
- Aug 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
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What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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Attacks
What attackers are doing with it
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Public exploit references
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Technologies
Your stack
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Your stack
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