{"id":"CVE-2026-90104","state":"PUBLISHED","title":"NFSv4.1: zero referring call lists before decoding","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4.1: zero referring call lists before decoding\n\ndecode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so\neach referring_call_list starts uninitialized. decode_rc_list() assigns\nrcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero\nreferring calls therefore leaves the pointer uninitialized, and\nnfs4_callback_sequence() later passes stale slab contents to kfree().\n\nAllocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is\nNULL from the beginning, including valid empty referring call lists.","publishedAt":"2026-09-17T16:06:14.191Z","updatedAt":"2026-10-30T12:34:08.837Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"810f6b3a29ac96fdc16909132b31627dae6824c2","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"ed54460caf5b5aa65ec03c9a6032d831f39f19f5","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"7510a5b9edec9d9536a4e69f10edfb2592e6cf7f","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"f4d23937e1c41995c2f54af26c89b5e48a41c299","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"f31f3c042e024aef437cda42f0424ae8d4594b6c","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"8fa4804fe62ca4155a2d8fc2789d630376cbf2fc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/callback_xdr.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.31","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.31","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":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/callback_xdr.c"]}],"references":["https://git.kernel.org/stable/c/810f6b3a29ac96fdc16909132b31627dae6824c2","https://git.kernel.org/stable/c/ed54460caf5b5aa65ec03c9a6032d831f39f19f5","https://git.kernel.org/stable/c/7510a5b9edec9d9536a4e69f10edfb2592e6cf7f","https://git.kernel.org/stable/c/f4d23937e1c41995c2f54af26c89b5e48a41c299","https://git.kernel.org/stable/c/f31f3c042e024aef437cda42f0424ae8d4594b6c","https://git.kernel.org/stable/c/8fa4804fe62ca4155a2d8fc2789d630376cbf2fc"],"weaknesses":[],"ingestedAt":"2026-10-30T12:52:04.348Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/90xxx/CVE-2026-90104.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-90104","state":"PUBLISHED","datePublished":"2026-09-17T16:06:14.191Z","dateUpdated":"2026-10-30T12:34:08.837Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-11T19:38:34.786Z"},"containers":{"cna":{"title":"NFSv4.1: zero referring call lists before decoding","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4.1: zero referring call lists before decoding\n\ndecode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so\neach referring_call_list starts uninitialized. decode_rc_list() assigns\nrcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero\nreferring calls therefore leaves the pointer uninitialized, and\nnfs4_callback_sequence() later passes stale slab contents to kfree().\n\nAllocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is\nNULL from the beginning, including valid empty referring call lists."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"810f6b3a29ac96fdc16909132b31627dae6824c2","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"ed54460caf5b5aa65ec03c9a6032d831f39f19f5","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"7510a5b9edec9d9536a4e69f10edfb2592e6cf7f","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"f4d23937e1c41995c2f54af26c89b5e48a41c299","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"f31f3c042e024aef437cda42f0424ae8d4594b6c","versionType":"git"},{"version":"4aece6a19cf7f474f15eb861ba74db4479884ce3","status":"affected","lessThan":"8fa4804fe62ca4155a2d8fc2789d630376cbf2fc","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/callback_xdr.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.31","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.31","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":"6.18.57","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.6","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfs/callback_xdr.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/810f6b3a29ac96fdc16909132b31627dae6824c2"},{"url":"https://git.kernel.org/stable/c/ed54460caf5b5aa65ec03c9a6032d831f39f19f5"},{"url":"https://git.kernel.org/stable/c/7510a5b9edec9d9536a4e69f10edfb2592e6cf7f"},{"url":"https://git.kernel.org/stable/c/f4d23937e1c41995c2f54af26c89b5e48a41c299"},{"url":"https://git.kernel.org/stable/c/f31f3c042e024aef437cda42f0424ae8d4594b6c"},{"url":"https://git.kernel.org/stable/c/8fa4804fe62ca4155a2d8fc2789d630376cbf2fc"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - xs_read_stream_call()/rpcrdma_bc_receive_call() deliver a backchannel RPC_CALL on the established NFSv4.1 TCP or RPC/RDMA session into nfs4_callback_compound → process_op → decode_cb_sequence_args(); the attacker-controlled bytes are the CB_SEQUENCE csa_nrclists and rcl_nrefcalls XDR fields sent by the NFS server.\nAC:L - A single well-formed CB_SEQUENCE with csa_nrclists≥1 and decode_rc_list() seeing rcl_nrefcalls==0 skips the rcl_refcalls assignment and still returns 0; nfs4_callback_sequence() then kfree()s that stale pointer. Empty referring_call_list4 is valid RFC 5661 XDR, so no race or victim-only state is required.\nPR:N - nfs_callback_authenticate() accepts RPC_AUTH_UNIX on the NFSv4.1 backchannel, and decode_cb_sequence_args() runs in process_op() before nfs4_find_client_sessionid(); the connected NFS server needs no account or capability on the client to send CB_SEQUENCE.\nUI:N - After nfs4_init_callback() has attached the backchannel (boot-time, autofs, or Kubernetes NFSv4.1 mounts), the server unilaterally sends CB_SEQUENCE; nfs4_callback_sequence() kfree()s rcl_refcalls with no further victim open, mount, or click.\nS:U - kfree of the stale rcl_refcalls pointer corrupts the NFS client's kmalloc heap in the same host kernel; it does not cross a VM, IOMMU, or guest/host boundary.\nC:H - nfs4_callback_sequence() kfree()s uninitialized rcl_refcalls left by kmalloc_objs() of csa_rclists when rcl_nrefcalls was 0. A prior CB_SEQUENCE that allocated then freed rcl_refcalls can leave that pointer in the reused slab object, a heap double-free/UAF read primitive.\nI:H - The same kfree of stale rcl_refcalls is a slab double-free of the referring_call array (size chosen by the attacker's earlier nrefcalls). Reclaim or spraying a replacement object over that free yields an arbitrary kernel write / control-flow hijack primitive.\nA:H - kfree of a non-NULL garbage rcl_refcalls pointer from a successful decode_cb_sequence_args() of an empty referring_call_list causes SLUB to BUG, oops, or panic even when the double-free is not fully exploited."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:34:08.837Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.6.160"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.12.114"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"6.18.57"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"7.2.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.31","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}