{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64296","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T15:36:31.778Z","datePublished":"2026-07-25T08:49:33.847Z","dateUpdated":"2026-08-17T04:52:53.790Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T04:52:53.790Z"},"descriptions":[{"lang":"en","value":"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->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."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - A crafted exFAT image is reached through local pathname operations such as openat(), which call exfat_lookup(), exfat_find(), and exfat_find_dir_entry(); loop-backed images make physical access unnecessary.\nAC:L - The attacker controls the stream hash, declared name length, extension-entry sequence, and early NUL characters, making the out-of-bounds access deterministic without a race or uncontrollable condition.\nPR:L - Although exFAT cannot be mounted directly from a user namespace, common storage brokers allow an active unprivileged user to mount a loop-backed non-system image. Once mounted, triggering lookup requires only ordinary directory search access and no capability.\nUI:N - The unprivileged attacker can mount the crafted image through such a storage broker and issue the triggering pathname lookup without another user's action.\nS:U - The vulnerable filesystem parser and the affected kernel memory belong to the same security authority; ordinary kernel privilege escalation does not change scope.\nC:H - Crafted entries cause repeated out-of-bounds 16-bit reads across the kernel stack, and filename comparison behavior can provide an oracle over attacker-selected stack locations. Successful control-flow corruption could disclose arbitrary kernel memory.\nI:H - The function writes zero beyond the stack buffer, and the successful-match path can jump to found without restoring the overwritten value. Attacker-selected stack control data or pointers can therefore be corrupted, potentially enabling arbitrary writes or kernel code execution.\nA:H - Zero-length fragments can advance the pointer until it reaches a stack guard page or corrupts control data, causing an oops, panic, or persistent lockup."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/exfat/dir.c"],"versions":[{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"72a2589d82eb001c94b74bcfe6f9a599bd9bef60","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"cf85180b8a015029ee147694eaf4e0b3537e9432","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"727bf7783a2936ffd55c628dddfd69343e511dcf","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"33c0b96d7e1672be1de0053786637ea46fb81507","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"c8e041c68c0bbb73aa62371ee63947bb6949d8b2","status":"affected","versionType":"git"},{"version":"ca06197382bde0a3bc20215595d1c9ce20c6e341","lessThan":"3a1230e7b043c62737b05a3e9275ca83a43ad20a","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/exfat/dir.c"],"versions":[{"version":"5.7","status":"affected"},{"version":"0","lessThan":"5.7","status":"unaffected","versionType":"semver"},{"version":"5.10.261","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.212","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.96","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.39","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.4","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.10.261"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"5.15.212"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.7","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60"},{"url":"https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4"},{"url":"https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432"},{"url":"https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0"},{"url":"https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf"},{"url":"https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507"},{"url":"https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2"},{"url":"https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a"}],"title":"exfat: bound uniname advance in exfat_find_dir_entry()","x_generator":{"engine":"bippy-1.2.0"}}}}