{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89690", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.749Z", "datePublished": "2026-09-11T19:46:10.632Z", "dateUpdated": "2026-10-19T08:51:03.524Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:51:03.524Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: defer vfree of compound ops to fix rpc_status UAF\n\nThe rpc_status netlink dumpit walks every in-flight svc_rqst under\nrcu_read_lock and, for NFSv4 requests, reads opnums out of\nargs->ops[]. But args->ops is a separate vmalloc buffer freed\nsynchronously by vfree() in nfsd4_release_compoundargs() at the end\nof every compound. The dumpit's rcu_read_lock pins the svc_rqst\nstruct itself (freed via kfree_rcu), but nothing defers the vfree\nof the ops buffer across the RCU grace period. A concurrent compound\ncompletion can therefore free the buffer while the dumpit is reading\nit — a use-after-free on vmalloc memory.\n\nThe trailing seqcount recheck (smp_load_acquire of rq_status_counter)\ncannot undo a load that already retired against freed memory.\n\nFix by replacing vfree(args->ops) with kvfree_rcu_mightsleep(), which\ndefers the free until after an RCU grace period. This makes the\nexisting rcu_read_lock in the dumpit sufficient to protect the read.\nThe tradeoff is that completed compound ops buffers (up to\n200 * sizeof(struct nfsd4_op)) persist in memory slightly longer,\nacross one grace period, before being reclaimed." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The UAF is in nfsd_nl_rpc_status_get_dumpit(), reached only via the NFSD_CMD_RPC_STATUS_GET generic-netlink dump over AF_NETLINK. Remote NFSv4 compounds drive the vfree of args->ops in nfsd4_release_compoundargs() but never enter dumpit, so exploitation requires local access.\nAC:L - The attacker fully controls the dumpit reader and can loop it while sending NFSv4 COMPOUNDs with more than eight ops so nfsd vcalloc()s args->ops and vfree()s it on every request. That is an attacker-driven race; the seqcount recheck does not prevent the already-retired load against freed vmalloc memory.\nPR:L - NFSD_CMD_RPC_STATUS_GET is registered with GENL_CMD_CAP_DUMP and no GENL_ADMIN_PERM, so any unprivileged process in the nfsd network namespace can invoke the dump. Exploitation does not require CAP_NET_ADMIN or root.\nUI:N - The attacker issues the netlink dump themselves and can generate the concurrent NFSv4 compounds; no separate victim action such as mounting a filesystem or opening a device is required.\nS:U - This is a kernel vmalloc use-after-free in nfsd on the local host. Impact stays inside the kernel's security authority and does not cross a VM, IOMMU, or other security boundary.\nC:H - dumpit reads opnums from the vfree'd args->ops[] buffer and returns them to userspace via NFSD_A_RPC_STATUS_COMPOUND_OPS. A kernel UAF with reuse of that vmalloc region yields an arbitrary-read primitive, which CVSS treats as high confidentiality impact.\nI:H - This is a use-after-free of a vmalloc compound-ops array that dumpit walks under rcu_read_lock while nfsd vfree()s it. UAF of attacker-reclaimable kernel memory enables corruption and control-flow hijacking primitives, not crash-only impact.\nA:H - Use-after-free of a vfree'd vmalloc buffer while dumpit still loads args->ops[j].opnum oopses or panics the kernel even if the UAF is not turned into code execution, fully disrupting the NFS server host." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nfsd/nfs4xdr.c" ], "versions": [ { "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c", "lessThan": "48f72aff24f7a7329209dc6cbc27c869f3e3595c", "status": "affected", "versionType": "git" }, { "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c", "lessThan": "6703199f4d7e7f37d6a726a849eb358e8fae72fb", "status": "affected", "versionType": "git" }, { "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c", "lessThan": "19413ccc45070a7270b9e25c2a258daf7f91de42", "status": "affected", "versionType": "git" }, { "version": "bd9d6a3efa9709e653aafbeb859289feccb8e70c", "lessThan": "fca26a3fc19ed02278aa2a150af82d43db0302cb", "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/nfsd/nfs4xdr.c" ], "versions": [ { "version": "6.7", "status": "affected" }, { "version": "0", "lessThan": "6.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "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": "6.7", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/48f72aff24f7a7329209dc6cbc27c869f3e3595c" }, { "url": "https://git.kernel.org/stable/c/6703199f4d7e7f37d6a726a849eb358e8fae72fb" }, { "url": "https://git.kernel.org/stable/c/19413ccc45070a7270b9e25c2a258daf7f91de42" }, { "url": "https://git.kernel.org/stable/c/fca26a3fc19ed02278aa2a150af82d43db0302cb" } ], "title": "nfsd: defer vfree of compound ops to fix rpc_status UAF", "x_generator": { "engine": "bippy-1.2.0" } } } }