{"id":"CVE-2026-64296","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: bound uniname advance in exfat_find_dir_entry()\n\nIn exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the\noutput pointer by a fixed amount whil…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: bound uniname advance in exfat_find_dir_entry()\n\nIn exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the\noutput pointer by a fixed amount whil…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","published":"2026-07-25","updated":"2026-07-27","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64296","references":[{"url":"https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00169,"epssPercentile":0.06593,"ingestedAt":"2026-07-27T06:16:50.168Z","slug":"CVE-2026-64296","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nexfat: bound uniname advance in exfat_find_dir_entry()\n\nIn exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the\noutput pointer by a fixed amount while the loop guard only tracks the\naccumulated name length:\n\n\tif (++order == 2)\n\t\tuniname = p_uniname->name;\n\telse\n\t\tuniname += EXFAT_FILE_NAME_LEN;\n\tlen = exfat_extract_uni_name(ep, entry_uniname);\n\tname_len += len;\n\tunichar = *(uniname+len);\n\t*(uniname+len) = 0x0;\n\nuniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len\ngrows only by the actual extracted length, which is shorter when a name\nfragment contains an early NUL.  The only guard is\n`name_len >= MAX_NAME_LENGTH`, so a crafted directory with many short\nname fragments lets uniname run far past the\np_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small,\ncausing an out-of-bounds read and write at *(uniname+len).\n\nThe sibling extractor exfat_get_uniname_from_ext_entry() already stops\non a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard\nadded in commit d42334578eba (\"exfat: check if filename entries exceeds\nmax filename length\")); exfat_find_dir_entry() never got the\nequivalent.  Track the per-entry write offset as a count and reject a\nfragment once the offset, or the offset plus the extracted length, would\nexceed MAX_NAME_LENGTH, before forming the output pointer.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}