CVE-2026-91189
The GUIX binary resource loader never checks that a font page's glyph range is well formed
- Risk score
- 43/100
- CVSS
- 7.1 v4.0
- Exploit chance (30 days)
- 0.1%
- Published
- 20 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 ve…
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 7.1 high
References
Original 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.
Last activity 20 Oct 2026. Patch Forecast updates every hour.