CVE-2026-91189 The GUIX binary resource loader never checks that a font page's glyph range is well formed.
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-91189?
CVE-2026-91189 is a high-severity vulnerability in Eclipse ThreadX - GUIX, published on 20 Oct 2026.
Official 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.
Which versions are affected by CVE-2026-91189?
How do I fix CVE-2026-91189?
No fix has been published for CVE-2026-91189 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-91189 being exploited?
There is no known exploitation of CVE-2026-91189 in the wild and no public exploit code.
Sources
Also known as GHSA-hgcj-22cg-4hfv.