{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90149", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.789Z", "datePublished": "2026-09-17T16:06:43.671Z", "dateUpdated": "2026-10-21T12:50:06.603Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:50:06.603Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers\n\nflexfiles accepts NFSv4.0 data servers, but two NFSv4 code paths assume\nthe data server client has a session. Unlike NFSv4.1+, an NFSv4.0 client\nhas no session (clp->cl_session is NULL; it uses clp->cl_slot_tbl), so\nI/O to a v4.0 flexfiles DS oopses:\n\n - nfs4_init_ds_session() dereferences clp->cl_session->session_state\n while seeding the DS lease. It also only seeds cl_lease_time when\n NFS4_SESSION_INITING is set; without a session that never happens, so\n cl_lease_time stays 0 and nfs4_renew_state() busy-loops, requeuing\n every 5 seconds. Seed the lease whenever there is no session and\n return before touching session state.\n\n - ff_layout_async_handle_error_v4() dereferences\n clp->cl_session->fc_slot_table on every DS I/O error. Fall back to the\n v4.0 transport slot table (clp->cl_slot_tbl) when there is no session." } ], "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 - A malicious NFSv4.1 MDS sets version=4 and minor_version=0 in the flexfiles GETDEVICEINFO device-addr body; nfs4_ff_alloc_deviceid_node() accepts that pair, nfs4_set_ds_client() builds a session-less v4.0 nfs_client, and nfs4_init_ds_session() then crashes on DS connect. GETDEVICEINFO is NFS/RPC over TCP.\nAC:L - nfs4_ff_alloc_deviceid_node() explicitly allows an NFSv4.0 DS (version==4 && minor_version<3). The MDS sets those two GETDEVICEINFO XDR words, and the next read/write that reaches nfs4_ff_layout_prepare_ds() → nfs4_init_ds_session() dereferences the NULL cl_session with no race.\nPR:N - The attacker is the remote MDS (or an on-path injector of GETDEVICEINFO replies) and needs no account or capability on the victim client; the client authenticates to the server, not the reverse.\nUI:N - On an already-mounted pNFS flexfiles share, ordinary file I/O drives LAYOUTGET then GETDEVICEINFO; the MDS can return a v4.0 DS in that GETDEVICEINFO and nfs4_init_ds_session() oopses with no further victim action such as mounting a new image.\nS:U - The NULL dereference oopses the NFS client kernel itself and does not cross a VM, IOMMU, or other security-authority boundary.\nC:N - nfs4_init_ds_session() loads clp->cl_session->session_state when cl_session is NULL, a pure NULL-pointer fault at a low offset of struct nfs4_session, with no out-of-bounds read or other disclosure.\nI:N - The same NULL load of cl_session (and cl_session->fc_slot_table in ff_layout_async_handle_error_v4) faults before any store; this is not a UAF, overflow, or type confusion that could yield a write primitive.\nA:H - Dereferencing the NULL cl_session in nfs4_init_ds_session() on DS connect, or cl_session->fc_slot_table in ff_layout_async_handle_error_v4 on a DS I/O error, produces a kernel oops that takes down the client." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nfs/flexfilelayout/flexfilelayout.c", "fs/nfs/nfs4session.c" ], "versions": [ { "version": "a7878ca140084ec267ede48fce64d7e60f6d873e", "lessThan": "336b6da10021c69a8f273bbacdf7432fdc89a06f", "status": "affected", "versionType": "git" }, { "version": "a7878ca140084ec267ede48fce64d7e60f6d873e", "lessThan": "5527af72b0100c94287bfec901b6313eeac567ca", "status": "affected", "versionType": "git" }, { "version": "a7878ca140084ec267ede48fce64d7e60f6d873e", "lessThan": "163c16e01f53fc8eb8d0f3484ae6c382265ecbbd", "status": "affected", "versionType": "git" }, { "version": "a7878ca140084ec267ede48fce64d7e60f6d873e", "lessThan": "436a214514e24103159aea455147d58b44a8a585", "status": "affected", "versionType": "git" }, { "version": "a7878ca140084ec267ede48fce64d7e60f6d873e", "lessThan": "2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc", "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/nfs/flexfilelayout/flexfilelayout.c", "fs/nfs/nfs4session.c" ], "versions": [ { "version": "4.12", "status": "affected" }, { "version": "0", "lessThan": "4.12", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "4.12", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.12.114" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.18.52" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/336b6da10021c69a8f273bbacdf7432fdc89a06f" }, { "url": "https://git.kernel.org/stable/c/5527af72b0100c94287bfec901b6313eeac567ca" }, { "url": "https://git.kernel.org/stable/c/163c16e01f53fc8eb8d0f3484ae6c382265ecbbd" }, { "url": "https://git.kernel.org/stable/c/436a214514e24103159aea455147d58b44a8a585" }, { "url": "https://git.kernel.org/stable/c/2b03ebbf8d5e8f6af4ecd6c65375232dd1ec32cc" } ], "title": "NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers", "x_generator": { "engine": "bippy-1.2.0" } } } }