{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-37954", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.973Z", "datePublished": "2025-05-20T16:01:48.561Z", "dateUpdated": "2026-08-05T11:58:37.074Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:58:37.074Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: Avoid race in open_cached_dir with lease breaks\n\nA pre-existing valid cfid returned from find_or_create_cached_dir might\nrace with a lease break, meaning open_cached_dir doesn't consider it\nvalid, and thinks it's newly-constructed. This leaks a dentry reference\nif the allocation occurs before the queued lease break work runs.\n\nAvoid the race by extending holding the cfid_list_lock across\nfind_or_create_cached_dir and when the result is checked." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The race is driven by an unsolicited SMB2 lease-break packet from the remote server, dispatched straight from the cifs demultiplex thread into cached_dir_lease_break() (fs/smb/client/smb2misc.c:655) with no pending request. A malicious/compromised SMB server, or an off-path attacker injecting frames on an unsigned SMB connection, controls exactly when that half of the race fires.\nAC:L - The attacker controls both sides — the server chooses when and how often to send lease breaks (unlimited retries, one per re-cached directory), while the client's routine stat()/getdents() traffic, which the server can itself provoke by breaking leases to force re-opens, repeatedly traverses the unlocked window. The same class of race in this file was reproduced by its author with two ordinary shell loops.\nPR:N - The attacking SMB server holds no privileges or credentials on the victim client; it merely answers a share the client has already mounted. The local half needs nothing beyond stat() or readdir() on the mount, available to any unprivileged account with no capabilities.\nUI:N - The mount is a pre-existing configuration, not an exploit-time action, and no deliberate victim participation is needed — ordinary background directory access from any process supplies the local half, and the server can force re-opens on demand by breaking the lease.\nS:U - The leaked dentry/inode references, corrupted superblock teardown and crash are all confined to the client kernel's own security authority. No VM, IOMMU or sandbox boundary is crossed.\nC:N - The defect is a lost reference count; no memory is read out of bounds and no kernel data is copied to the attacker. The only pointer surfaced is in a WARN message, which is %p-hashed and requires dmesg access.\nI:N - The attacker gains no write primitive — nothing attacker-controlled is stored anywhere, and the cfid kref accounting remains balanced in every interleaving I traced, so no double-free or type confusion is reachable.\nA:H - Each won race permanently leaks a dentry, its inode and an open server handle, and the affected mount can never be torn down: unmount hits WARN(1, \"BUG: Dentry ... still in use\") in umount_check() and then \"VFS: Busy inodes after unmount\", which is a hard BUG()/oops under CONFIG_BUG_ON_DATA_CORRUPTION and a panic under panic_on_warn. Otherwise the superblock is freed with live VFS_PTR_POISON'd inodes that crash on any later access, on top of unbounded, unreclaimable memory growth." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/cached_dir.c" ], "versions": [ { "version": "81ba10959970d15c388bf29866b01b62f387e6a3", "lessThan": "2ed98e89ebc2e1bc73534dc3c18cb7843a889ff9", "status": "affected", "versionType": "git" }, { "version": "81ba10959970d15c388bf29866b01b62f387e6a3", "lessThan": "571dcf3d27b24800c171aea7b5e04ff06d10e2e9", "status": "affected", "versionType": "git" }, { "version": "81ba10959970d15c388bf29866b01b62f387e6a3", "lessThan": "2407265dc32bc8cc45b62a612c2a214ba9038e8b", "status": "affected", "versionType": "git" }, { "version": "81ba10959970d15c388bf29866b01b62f387e6a3", "lessThan": "3ca02e63edccb78ef3659bebc68579c7224a6ca2", "status": "affected", "versionType": "git" }, { "version": "436be190fbf81e5d84040dabf9cb7be06a94dc5d", "status": "affected", "versionType": "git" }, { "version": "6.5.10", "lessThan": "6.6", "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/cached_dir.c" ], "versions": [ { "version": "6.6", "status": "affected" }, { "version": "0", "lessThan": "6.6", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.91", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.29", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14.7", "lessThanOrEqual": "6.14.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15", "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": "6.6", "versionEndExcluding": "6.6.91" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.12.29" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.14.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6", "versionEndExcluding": "6.15" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2ed98e89ebc2e1bc73534dc3c18cb7843a889ff9" }, { "url": "https://git.kernel.org/stable/c/571dcf3d27b24800c171aea7b5e04ff06d10e2e9" }, { "url": "https://git.kernel.org/stable/c/2407265dc32bc8cc45b62a612c2a214ba9038e8b" }, { "url": "https://git.kernel.org/stable/c/3ca02e63edccb78ef3659bebc68579c7224a6ca2" } ], "title": "smb: client: Avoid race in open_cached_dir with lease breaks", "x_generator": { "engine": "bippy-1.2.0" } } } }