{"id":"CVE-2026-91189","aliases":["EUVD-2026-105040","GHSA-hgcj-22cg-4hfv"],"status":"published","title":"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","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 \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.","severity":{"version":"4.0","score":7.1,"vector":"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00135,"percentile":0.02981,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-190","CWE-680","CWE-787"],"published":"2026-10-20T14:53:44Z","modified":"2026-10-28T02:30:47Z","products":[{"vendor":"eclipse foundation","product":"eclipse threadx - guix"}],"references":[{"url":"https://github.com/eclipse-threadx/guix/security/advisories/GHSA-hgcj-22cg-4hfv","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/91xxx/CVE-2026-91189.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-91189","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-91189","title":"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","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 \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.","status":"published","published":"2026-10-20T14:53:44.86Z","modified":"2026-10-20T15:25:24.066Z","cvss":[{"version":"4.0","score":7.1,"vector":"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","level":"high","assessor":"cna"}],"cwes":["CWE-190","CWE-680","CWE-787"],"updated_at":"2026-11-02T14:19:53.115938Z"}],"euvd":[{"id":"EUVD-2026-105040","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 \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.","status":"published","published":"2026-10-20T14:53:44Z","modified":"2026-10-20T15:25:24Z","cvss":[{"version":"4.0","score":7.1,"vector":"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","level":"high"}],"updated_at":"2026-11-02T16:59:43.975979Z"}],"nvd":[{"id":"CVE-2026-91189","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 \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.","status":"published","published":"2026-10-20T15:17:36.167Z","modified":"2026-10-20T19:48:50.25Z","cvss":[{"version":"4.0","score":7.1,"vector":"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","level":"high","assessor":"secondary"}],"cwes":["CWE-190","CWE-680","CWE-787"],"updated_at":"2026-11-02T14:13:01.161484Z"}],"osv":[{"id":"CVE-2026-91189","title":"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","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 \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.","status":"published","published":"2026-10-20T14:53:44.86Z","modified":"2026-10-28T02:30:47.810058875Z","cvss":[{"version":"4.0","score":7.1,"vector":"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","level":"high"}],"cwes":["CWE-190","CWE-680","CWE-787"],"updated_at":"2026-11-02T15:45:20.269367Z"}]}}