{"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"}}]}}