{"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"}}}}

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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."}], "id": "CVE-2026-64296", "lastModified": "2026-08-17T05:17:29.203", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-07-25T10:17:10.390", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "NVD-CWE-noinfo"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: exfat: bound uniname advance in exfat_find_dir_entry()", "id": "2507295", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2507295"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.0", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-125", "details": ["A flaw was found in the Linux kernel's exFAT filesystem driver. A local attacker could create a specially crafted directory with malformed name fragments. When the kernel processes this directory, an out-of-bounds read and write can occur, potentially leading to a denial of service or system instability. This vulnerability arises from incorrect boundary checks during the processing of directory entries."], "name": "CVE-2026-64296", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2026-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-64296\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-64296\nhttps://lore.kernel.org/linux-cve-announce/2026072505-CVE-2026-64296-f344@gregkh/T"], "threat_severity": "Important"}