CVE-2026-91189
HIGHDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
CVSS:4.0/AV:L/AC:H/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Exploit Intelligence
Low risk: more likely to be exploited than 3% of all known CVEs.
References
Related Vulnerabilities
Other CWE-190 (Integer Overflow) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2020-16040 | Medium | 6.5 | 100% | - | Fix |
| CVE-2019-11477 | High | 7.5 | 99% | - | Fix |
| CVE-2023-44443 | High | 7.8 | 94% | - | Fix |
| CVE-2014-0569 | High | 9.3 | 91% | - | - |
| CVE-2017-3599 | High | 7.5 | 90% | - | Fix |
| CVE-2023-21716 | Critical | 9.8 | 85% | - | Fix |
Common questions
How do I fix CVE-2026-91189?
No published fix for CVE-2026-91189 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-91189 being actively exploited?
Not that we know of. CVE-2026-91189 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.14% is the estimated probability that it will be exploited in the next 30 days. That is higher than 3% of all scored CVEs.
How severe is CVE-2026-91189?
CVE-2026-91189 has a CVSS v4 base score of 7.1, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-10-20.