{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31539", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.114Z", "datePublished": "2026-04-24T14:30:26.326Z", "dateUpdated": "2026-08-05T12:23:24.146Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:23:24.146Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: smbdirect: introduce smbdirect_socket.recv_io.credits.available\n\nThe logic off managing recv credits by counting posted recv_io and\ngranted credits is racy.\n\nThat's because the peer might already consumed a credit,\nbut between receiving the incoming recv at the hardware\nand processing the completion in the 'recv_done' functions\nwe likely have a window where we grant credits, which\ndon't really exist.\n\nSo we better have a decicated counter for the\navailable credits, which will be incremented\nwhen we posted new recv buffers and drained when\nwe grant the credits to the peer." } ], "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 - SMBDirect is reached by a remote RDMA peer through RDMA CM listeners on SMBDirect/SMB ports such as 5445 and 445. The ksmbd server path processes the affected negotiation and data-transfer credit handling from network-originated RDMA messages.\nAC:L - The issue is a receive-credit accounting race, but the remote peer can repeatedly drive both message arrival and credit-request/response behavior with crafted SMBDirect traffic. No unusual victim state or uncontrollable condition is required beyond an enabled SMBDirect RDMA deployment.\nPR:N - The server-side path accepts the RDMA connection and performs SMBDirect negotiation and data-transfer credit handling before SMB session authentication. A remote peer does not need SMB credentials to reach the vulnerable credit logic.\nUI:N - Exploitation against the server path requires only network/RDMA traffic from the attacker. No local user or administrator action is needed after the service is exposed.\nS:U - The impact remains within the kernel SMBDirect/SMB service security authority. There is no VM escape, IOMMU bypass, or cross-authority boundary crossing.\nC:N - The bug overgrants receive credits but does not expose a kernel read primitive; incoming payload bounds are checked before reassembly. An RDMA send without a posted receive should produce transport/RNR failure rather than disclose memory.\nI:N - The investigation did not identify an arbitrary write or memory-corruption primitive. The false credit causes receive-queue/transport state inconsistency, not attacker-controlled modification of kernel data.\nA:H - False credits can allow the peer to send when no real receive buffer is posted, causing RDMA QP/transport errors and SMBDirect disconnects with RNR retries disabled. Because this is remotely and unauthenticatedly repeatable against the exposed SMBDirect service, availability impact is high." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/common/smbdirect/smbdirect_socket.h" ], "versions": [ { "version": "5fb9b459b3686e366640edd4e62805ef7b4de927", "lessThan": "e811e60e1cc79923c4388146eb1fa26a7482731e", "status": "affected", "versionType": "git" }, { "version": "5fb9b459b3686e366640edd4e62805ef7b4de927", "lessThan": "f99996870222b598914a1f49d7375dc23752c237", "status": "affected", "versionType": "git" }, { "version": "5fb9b459b3686e366640edd4e62805ef7b4de927", "lessThan": "6e3c5052f9686192e178806e017b7377155f4bab", "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/common/smbdirect/smbdirect_socket.h" ], "versions": [ { "version": "6.18", "status": "affected" }, { "version": "0", "lessThan": "6.18", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.11", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.19.1", "lessThanOrEqual": "6.19.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0", "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", "versionEndExcluding": "6.18.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "6.19.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18", "versionEndExcluding": "7.0" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e811e60e1cc79923c4388146eb1fa26a7482731e" }, { "url": "https://git.kernel.org/stable/c/f99996870222b598914a1f49d7375dc23752c237" }, { "url": "https://git.kernel.org/stable/c/6e3c5052f9686192e178806e017b7377155f4bab" } ], "title": "smb: smbdirect: introduce smbdirect_socket.recv_io.credits.available", "x_generator": { "engine": "bippy-1.2.0" } } } }