{"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":"2026-09-13T06:33:14.771Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:33:14.771Z"},"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-rc1","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-rc1"}]}]}],"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"}}}}