{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89639", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.740Z", "datePublished": "2026-09-11T19:45:32.532Z", "dateUpdated": "2026-10-19T08:50:11.190Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:50:11.190Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC\n\ncifs_do_truncate() is invoked from cifs_open() without i_rwsem, so it\ncannot use cifs_resize_file_locked() to perform a proper fscache cookie\nresize. Instead, add cifs_invalidate_cache() after cifs_setsize().\n\ncifs_invalidate_cache() calls fscache_invalidate(), which works without\nholding i_rwsem: it unconditionally increments inval_counter and sets\nFSCACHE_COOKIE_NO_DATA_TO_READ, ensuring that stale cached data is not\nserved once the cookie is later activated by fscache_use_cookie().\nTruncation to zero leaves no valid cached data, making invalidation the\ncorrect semantic here." } ], "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:N", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - cifs_do_truncate() runs from cifs_open() on the SMB client during a local open/openat with O_TRUNC on a mounted CIFS share (fs/smb/client/), not from ksmbd/nfsd or demux-thread packet parsing; a remote SMB peer cannot invoke this path.\nAC:L - A write-capable open with O_TRUNC deterministically skips fscache invalidation, then the same cifs_open() activates the cookie via fscache_use_cookie(); the attacker can also hold another fd so the cookie is already active, with no race or layout outside their control.\nPR:L - O_TRUNC requires only MAY_WRITE on the target inode, which an ordinary local user has on an already-mounted CIFS share; no init-namespace root, CAP_SYS_ADMIN, or user-namespace mount of CIFS is needed.\nUI:N - The attacker issues open(O_TRUNC) and follow-on reads/writes themselves; on common fstab/autofs/CIFS-home deployments with the fsc option already set, no other user must mount the share or open the file.\nS:U - Stale data stays within the local CIFS client's fscache and the same SMB file's contents; this is not a VM escape, IOMMU bypass, or other cross-authority boundary crossing.\nC:H - After O_TRUNC the cookie is activated without FSCACHE_COOKIE_NO_DATA_TO_READ, so later reads (including holes after a size-extending write) can return the full previously truncated file contents that should have been discarded.\nI:H - The same stale cookie presents discarded bytes as current file data and can persist them to the SMB server via netfs read-modify-write/writeback, fully replacing zeros or newly written contents on that file.\nA:N - The flaw is fscache coherency only; it does not oops, panic, deadlock, or exhaust kernel resources, so host availability is unaffected." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/file.c" ], "versions": [ { "version": "efbcecdecefc26fa062c0e8210533ccad7d6bd4a", "lessThan": "8b9b10fe5b8b492b27b9f4546742ea541a650213", "status": "affected", "versionType": "git" }, { "version": "fa724e235cfdb0fb0bb427d0f9dfe864ae27403e", "lessThan": "81fc3868a7f726980ff845c1d0d271051e5f0f45", "status": "affected", "versionType": "git" }, { "version": "fa724e235cfdb0fb0bb427d0f9dfe864ae27403e", "lessThan": "364b183230586a62660a7280c1eb20138338eeb5", "status": "affected", "versionType": "git" }, { "version": "6838bcac954487cc0a3c8a4ee1b3a3a30e244dc9", "status": "affected", "versionType": "git" }, { "version": "75640976cf474eb41682a13f2dbe9534ac26ca50", "status": "affected", "versionType": "git" }, { "version": "3513f3931c579ba2a715784c6dedc59e0d9282ee", "status": "affected", "versionType": "git" }, { "version": "6.18.44", "lessThan": "6.18.50", "status": "affected", "versionType": "semver" }, { "version": "6.12.105", "lessThan": "6.13", "status": "affected", "versionType": "semver" }, { "version": "7.1.8", "lessThan": "7.2", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/file.c" ], "versions": [ { "version": "7.2", "status": "affected" }, { "version": "0", "lessThan": "7.2", "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": "6.18.44", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.2", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.2", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.12.105" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.1.8" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8b9b10fe5b8b492b27b9f4546742ea541a650213" }, { "url": "https://git.kernel.org/stable/c/81fc3868a7f726980ff845c1d0d271051e5f0f45" }, { "url": "https://git.kernel.org/stable/c/364b183230586a62660a7280c1eb20138338eeb5" } ], "title": "cifs: use cifs_invalidate_cache() in cifs_do_truncate() for O_TRUNC", "x_generator": { "engine": "bippy-1.2.0" } } } }