{"id":"CVE-2025-39933","state":"PUBLISHED","title":"smb: client: let recv_done verify data_offset, data_length and remaining_data_length","description":"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.","publishedAt":"2025-10-04T07:30:57.496Z","updatedAt":"2026-10-30T12:22:38.495Z","severity":{"score":9.4,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"fdc23a47be015fba915c4f9dfd43c65ad4829a35","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"f23d5c6b7540ec9b1e73a8ea3b2ae9045248d728","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"241e58de23e7c1bbb9bee526c17d9a0f2a90fbad","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"581fb78e0388b78911b0c920e4073737090c8b5f","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"f57e53ea252363234f86674db475839e5b87102e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smbdirect.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.9","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smbdirect.c"]}],"references":["https://git.kernel.org/stable/c/fdc23a47be015fba915c4f9dfd43c65ad4829a35","https://git.kernel.org/stable/c/f23d5c6b7540ec9b1e73a8ea3b2ae9045248d728","https://git.kernel.org/stable/c/241e58de23e7c1bbb9bee526c17d9a0f2a90fbad","https://git.kernel.org/stable/c/581fb78e0388b78911b0c920e4073737090c8b5f","https://git.kernel.org/stable/c/f57e53ea252363234f86674db475839e5b87102e"],"weaknesses":[],"ingestedAt":"2026-10-30T12:40:04.423Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/39xxx/CVE-2025-39933.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-39933","state":"PUBLISHED","datePublished":"2025-10-04T07:30:57.496Z","dateUpdated":"2026-10-30T12:22:38.495Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T07:20:57.148Z"},"containers":{"cna":{"title":"smb: client: let recv_done verify data_offset, data_length and remaining_data_length","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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"fdc23a47be015fba915c4f9dfd43c65ad4829a35","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"f23d5c6b7540ec9b1e73a8ea3b2ae9045248d728","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"241e58de23e7c1bbb9bee526c17d9a0f2a90fbad","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"581fb78e0388b78911b0c920e4073737090c8b5f","versionType":"git"},{"version":"f198186aa9bbd60fae7a2061f4feec614d880299","status":"affected","lessThan":"f57e53ea252363234f86674db475839e5b87102e","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smbdirect.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.160","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.114","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.16.9","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/smbdirect.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/fdc23a47be015fba915c4f9dfd43c65ad4829a35"},{"url":"https://git.kernel.org/stable/c/f23d5c6b7540ec9b1e73a8ea3b2ae9045248d728"},{"url":"https://git.kernel.org/stable/c/241e58de23e7c1bbb9bee526c17d9a0f2a90fbad"},{"url":"https://git.kernel.org/stable/c/581fb78e0388b78911b0c920e4073737090c8b5f"},{"url":"https://git.kernel.org/stable/c/f57e53ea252363234f86674db475839e5b87102e"}],"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."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:22:38.495Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"6.12.114"},{"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"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","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"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-11T18:44:07.641Z"}}]}}}