CVE-2026-91189
Received
Received - Intake
Buffer Overflow in GUIX Font Resource Loader
Vulnerability report for CVE-2026-91189, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-20
Last updated on: 2026-10-20
Assigner: Eclipse Foundation
Description
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.
CVSS Scores
EPSS Scores
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| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Eclipse | Foundation | Eclipse ThreadX - GUIX 0 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-190 | The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number. |
| CWE-787 | The product writes data past the end, or before the beginning, of the intended buffer. |
| CWE-680 | The product performs a calculation to determine how much memory to allocate, but an integer overflow can occur that causes less memory to be allocated than expected, leading to a buffer overflow. |
