{"id":"CVE-2026-91189","summary":"GUIX binary resource loader: unvalidated glyph range causes an integer underflow and a heap out-of-bounds write when loading an untrusted font or theme","details":"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 \u003e last_glyph` makes `last - first + 1` underflow to a very large unsigned count.\n\n\n\nThat 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.","aliases":["GHSA-hgcj-22cg-4hfv"],"modified":"2026-10-21T02:53:50.726426194Z","published":"2026-10-20T14:53:44.860Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91189.json","cna_assigner":"eclipse","cwe_ids":["CWE-190","CWE-680","CWE-787"]},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91189.json"},{"type":"ADVISORY","url":"https://github.com/eclipse-threadx/guix/security/advisories/GHSA-hgcj-22cg-4hfv"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91189"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/eclipse-threadx/guix","events":[{"introduced":"0"},{"last_affected":"52c1bb406843eb556d26dc28c65b13434f64e0ef"}],"database_specific":{"extracted_events":[{"range":[{"introduced":"0"},{"last_affected":"6.5.1.202602a"}],"source":"AFFECTED_FIELD","strategy":"StandardRange"}]}}],"versions":["v6.4.1_rel","v6.5.1.202602a_rel","v6.5.1.202602_rel","v6.4.5.202504_rel","v6.4.3.202503_rel","v6.4.2_rel","v6.4.0_rel","v6.3.0_rel","v6.2.1_rel","v6.2.0_rel","v6.1.12_rel","v6.1.11_rel","v6.1.10_rel","v6.1.9_rel","v6.1.8_rel","v6.1.7_rel","v6.1.6_rel","v6.1.5_rel","v6.1.4_rel","v6.1.3_rel","v6.1_rel","v6.0.2_rel","v6.0.1_rel","v6.0_rel"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-91189.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}