{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-39933", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.148Z", "datePublished": "2025-10-04T07:30:57.496Z", "dateUpdated": "2026-08-05T12:06:12.616Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:06:12.616Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: let recv_done verify data_offset, data_length and remaining_data_length\n\nThis is inspired by the related server fixes." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H", "baseScore": 9.4, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable code parses `smbdirect_data_transfer` headers received directly from a remote SMB server over RDMA, and iWARP/RoCEv2 are routable over ordinary IP networks (soft-iWARP/soft-RoCE need no special hardware). A malicious, compromised, or spoofed SMB Direct peer reaches `recv_done()` purely over the network.\nAC:L - The attacker writes `data_offset`/`data_length` as plain header fields in a single crafted data-transfer message; there is no race, no memory-layout precondition, and the out-of-bounds read is deterministic and repeatable at an offset of the attacker's choosing.\nPR:N - `recv_done()` switches to `SMBDIRECT_EXPECT_DATA_TRANSFER` as soon as the unauthenticated transport-level SMBD negotiate completes, so the malformed packet is processed before SMB2 NEGOTIATE/SESSION_SETUP and before any signing or encryption is established — the peer needs no credentials on the client.\nUI:N - Once an SMB Direct mount exists (including automounts, fstab, DFS referrals, and automatic reconnects), a hostile or compromised server can send the crafted frame at any time and the client processes it automatically in its receive-completion and demultiplex paths. No administrator or user action is required at the moment of attack.\nS:U - The out-of-bounds access, the disclosed data, and the resulting fault are all confined to the client kernel's own security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The unvalidated 32-bit `data_offset` makes `copy_to_iter()` read from an attacker-chosen address up to 4 GiB past a ~2 KB receive-buffer slab object, and the inflated `data_length` keeps that buffer at the queue head so `offset` advances on each call — allowing a remote peer to stream out large amounts of kernel memory, which is then delivered to userspace as SMB response/file content.\nI:L - There is no out-of-bounds write, but the client assembles and parses SMB2 responses built from out-of-bounds kernel memory, so connection state, file metadata, and page-cache contents returned to applications are driven by data the attacker caused the kernel to read from outside the intended buffer.\nA:H - A large `data_offset` faults on unmapped memory or a vmalloc guard page in the demultiplex/softirq path, and an inflated `data_length` desynchronizes `reassembly.data_length` so `_get_first_reassembly()` returns NULL and is immediately dereferenced — either way an oops (full panic with `panic_on_oops`) that tears down the mount." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/client/smbdirect.c" ], "versions": [ { "version": "f198186aa9bbd60fae7a2061f4feec614d880299", "lessThan": "581fb78e0388b78911b0c920e4073737090c8b5f", "status": "affected", "versionType": "git" }, { "version": "f198186aa9bbd60fae7a2061f4feec614d880299", "lessThan": "f57e53ea252363234f86674db475839e5b87102e", "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/smbdirect.c" ], "versions": [ { "version": "4.16", "status": "affected" }, { "version": "0", "lessThan": "4.16", "status": "unaffected", "versionType": "semver" }, { "version": "6.16.9", "lessThanOrEqual": "6.16.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17", "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": "4.16", "versionEndExcluding": "6.16.9" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.16", "versionEndExcluding": "6.17" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/581fb78e0388b78911b0c920e4073737090c8b5f" }, { "url": "https://git.kernel.org/stable/c/f57e53ea252363234f86674db475839e5b87102e" } ], "title": "smb: client: let recv_done verify data_offset, data_length and remaining_data_length", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2025-39933", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2026-06-10T20:40:59.041091Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-11T18:44:07.641Z" } } ] } }