{"id":"CVE-2026-6683","aliases":["EUVD-2026-40993","GHSA-74cg-p8q3-4c3q"],"status":"published","title":"FatFs Divide-by-Zero in exFAT Sync","description":"FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.","severity":{"version":"3.1","score":4.6,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00306,"percentile":0.23553,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-369"],"published":"2026-07-01T13:41:11Z","modified":"2026-10-25T17:10:00Z","products":[{"vendor":"chan","product":"fatfs"},{"vendor":"elm-chan","product":"fatfs"}],"references":[{"url":"https://www.runzero.com/blog/fatfs-bugs/","tags":["third-party-advisory","Third Party Advisory","Exploit"]},{"url":"https://github.com/runZeroInc/vulns-2026-fatfs-chance","tags":["technical-description","exploit","Third Party Advisory","Exploit"]},{"url":"https://elm-chan.org/fsw/ff/","tags":["product","Product"]},{"url":"https://www.runzero.com/advisories/fatfs-exfat-divide-by-zero-cve-2026-6683","tags":["third-party-advisory","Third Party Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-6683"},{"url":"https://elm-chan.org/fsw/ff"},{"url":"https://www.runzero.com/blog/fatfs-bugs"},{"url":"https://github.com/advisories/GHSA-74cg-p8q3-4c3q"}],"sources":{"cve":[{"id":"CVE-2026-6683","title":"FatFs Divide-by-Zero in exFAT Sync","description":"FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.","status":"published","published":"2026-07-01T13:41:11.337Z","modified":"2026-07-01T15:24:56.449Z","cvss":[{"version":"3.1","score":4.6,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-369"],"updated_at":"2026-11-02T13:50:04.986624Z"}],"euvd":[{"id":"EUVD-2026-40993","description":"FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.","status":"published","published":"2026-07-01T13:41:11Z","modified":"2026-07-01T15:24:56Z","cvss":[{"version":"3.1","score":4.6,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T18:20:19.446061Z"}],"ghsa":[{"id":"GHSA-74cg-p8q3-4c3q","title":"FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata...","description":"FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.","status":"published","published":"2026-07-01T15:35:20Z","modified":"2026-07-01T15:35:28Z","cvss":[{"version":"3.1","score":4.6,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-369"],"updated_at":"2026-11-02T15:09:08.409779Z"}],"nvd":[{"id":"CVE-2026-6683","description":"FatFs R0.16 and earlier contains a divide-by-zero in exFAT sync logic bug when crafted metadata causes n_fatent - 2 to be zero during write/sync operations. This maps to CWE-369 (Divide By Zero). Estimated CVSS v3.1 vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (4.6, Medium). Network-delivered update media can make this remote in some pipelines. The estimated CISA SSVC vectors are Exploitation: PoC, Technical Impact: Partial.","status":"published","published":"2026-07-01T15:17:12.443Z","modified":"2026-10-25T17:10:00.197Z","cvss":[{"version":"3.1","score":4.6,"vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"}],"cwes":["CWE-369"],"updated_at":"2026-11-02T14:12:27.199837Z"}]}}