{"id":"CVE-2026-64296","summary":"exfat: bound uniname advance in exfat_find_dir_entry()","details":"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 while the loop guard only tracks the\naccumulated name length:\n\n\tif (++order == 2)\n\t\tuniname = p_uniname-\u003ename;\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 \u003e= MAX_NAME_LENGTH`, so a crafted directory with many short\nname fragments lets uniname run far past the\np_uniname-\u003ename[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.","modified":"2026-07-28T04:03:03.373844888Z","published":"2026-07-25T08:49:33.847Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64296.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64296.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64296"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ca06197382bde0a3bc20215595d1c9ce20c6e341"},{"fixed":"72a2589d82eb001c94b74bcfe6f9a599bd9bef60"},{"fixed":"fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4"},{"fixed":"cf85180b8a015029ee147694eaf4e0b3537e9432"},{"fixed":"ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0"},{"fixed":"727bf7783a2936ffd55c628dddfd69343e511dcf"},{"fixed":"33c0b96d7e1672be1de0053786637ea46fb81507"},{"fixed":"c8e041c68c0bbb73aa62371ee63947bb6949d8b2"},{"fixed":"3a1230e7b043c62737b05a3e9275ca83a43ad20a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64296.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.7.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64296.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}