Vulnerability Description
The GUIX binary resource loader never checks that a font page's glyph range is well formed. `gx_page_header_first_glyph` and `gx_page_header_last_glyph` are read verbatim from the file and only the upper bound of `last_glyph` is validated, so a page declaring `first_glyph > last_glyph` makes `last - first + 1` underflow to a very large unsigned count. That count is multiplied by a glyph record size to reserve the load buffer, and the multiply is unchecked, so it wraps to a small value and the loader allocates a buffer far smaller than the data it is about to write. The load pass then recomputes the count in a narrower type and writes attacker-controlled glyph records into the undersized buffer.
Related Weaknesses (CWE)
References
FAQ
What is CVE-2026-91189?
CVE-2026-91189 is a documented vulnerability. The GUIX binary resource loader never checks that a font page's glyph range is well formed. `gx_page_header_first_glyph` and `gx_page_header_last_glyph` are read verbatim from the file and only the up...
How severe is CVE-2026-91189?
CVSS scoring is not yet available for CVE-2026-91189. Check NVD for updates.
Is there a patch for CVE-2026-91189?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.