{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89640", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.740Z", "datePublished": "2026-09-11T19:45:33.289Z", "dateUpdated": "2026-10-19T08:50:12.163Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:12.163Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: fix loff_t underflow in cifs_remap_file_range() when len == 0\n\nWith len == 0 (clone to EOF), the effective length is computed as:\n\n len = src_inode->i_size - off;\n\nIf off > i_size, this is a negative loff_t, corrupting the ByteCount\nin the FSCTL_DUPLICATE_EXTENTS_TO_FILE request and inverting the range\nin filemap_write_and_wait_range(). The existing off >= i_size check\nfires only after the ioctl has already been sent.\n\nSnapshot i_size_read() once for both the bounds check and the length\ncalculation, eliminating the TOCTOU and 32-bit torn-read risk. Reject\noff > src_size with -EINVAL. Treat off == src_size as a no-op,\nconsistent with __generic_remap_file_range_prep()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is in the CIFS client remap method, reached from the local FICLONERANGE/FICLONE ioctls through vfs_clone_file_range() on an already-mounted CIFS share, not from SMB packet parsing in ksmbd or the TCP stack.\nAC:L - An attacker fully controls src_offset and src_length and can set length to 0 with offset past i_size, so the loff_t underflow is deterministic and does not depend on a race or memory layout they cannot influence.\nPR:L - vfs_clone_file_range() only requires a regular source opened for read and a regular destination opened for write; any unprivileged user with those fds on a CIFS mount can issue FICLONERANGE without capabilities or init-namespace root.\nUI:N - The attacker opens their own CIFS files and issues the ioctl; no separate victim action such as mounting a share or opening a file is required once a typical enterprise/autofs CIFS mount exists.\nS:U - Impact stays inside the host kernel and the CIFS inode/page cache of the same OS security authority; this is not a VM, IOMMU, or sandbox boundary crossing.\nC:N - The underflow does not read attacker-inaccessible kernel or file data; it miscomputes a clone length and then truncates destination page cache and sends a bad FSCTL, with no out-of-bounds or UAF read primitive.\nI:H - Negative len wraps destend to a huge uoff_t so truncate_inode_pages_range() discards the destination file's page cache, including dirty folios not flushed in the inverted range, silently destroying buffered data, and the same value corrupts ByteCount in FSCTL_DUPLICATE_EXTENTS_TO_FILE.\nA:H - The same wrapped range and signed-to-u64 conversion can set a huge/negative EOF via smb2_set_file_size()/cifs_resize_file_locked() on duplicate-extents servers and leave netfs/pagecache state inconsistent, which can oops, hang, or deny access to the affected file and kernel paths." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/cifsfs.c" ], "versions": [ { "version": "04b38d601239b4d9be641b412cf4b7456a041c67", "lessThan": "f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4", "status": "affected", "versionType": "git" }, { "version": "04b38d601239b4d9be641b412cf4b7456a041c67", "lessThan": "7f62817fe049b0f3652518c1ba72631ec1e0a322", "status": "affected", "versionType": "git" }, { "version": "04b38d601239b4d9be641b412cf4b7456a041c67", "lessThan": "b098f5e5858797827666e6cd73033f52fc39b5f6", "status": "affected", "versionType": "git" }, { "version": "04b38d601239b4d9be641b412cf4b7456a041c67", "lessThan": "c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028", "status": "affected", "versionType": "git" }, { "version": "04b38d601239b4d9be641b412cf4b7456a041c67", "lessThan": "b057ca17b656345d04669cb87f2aff9b31d873db", "status": "affected", "versionType": "git" }, { "version": "04b38d601239b4d9be641b412cf4b7456a041c67", "lessThan": "6c322f5cf7476ded7a9a20f7be72462065a03c68", "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/smb/client/cifsfs.c" ], "versions": [ { "version": "4.5", "status": "affected" }, { "version": "0", "lessThan": "4.5", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.188", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.157", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "4.5", "versionEndExcluding": "6.1.188" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.6.157" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.5", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4" }, { "url": "https://git.kernel.org/stable/c/7f62817fe049b0f3652518c1ba72631ec1e0a322" }, { "url": "https://git.kernel.org/stable/c/b098f5e5858797827666e6cd73033f52fc39b5f6" }, { "url": "https://git.kernel.org/stable/c/c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028" }, { "url": "https://git.kernel.org/stable/c/b057ca17b656345d04669cb87f2aff9b31d873db" }, { "url": "https://git.kernel.org/stable/c/6c322f5cf7476ded7a9a20f7be72462065a03c68" } ], "title": "cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-89640", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2026-10-16T19:24:54.678656Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T19:26:45.931Z" } } ] } }