{"id":"CVE-2026-53394","state":"PUBLISHED","title":"nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: avoid leaking pre-allocated openowner on unconfirmed retry race\n\nWhen find_or_alloc_open_stateowner() encounters an unconfirmed owner, it\ncalls release_openowner() and sets oo = NULL. Control then falls through\npast the `if (oo)` guard -- which would have freed any pre-allocated\n`new` -- and unconditionally executes `new = alloc_stateowner(...)`. If\n`new` was already allocated on a prior iteration, the pointer is\nsilently overwritten and the previous allocation (slab object + owner\nname buffer) is leaked.\n\nThis requires a race: two NFSv4.0 OPEN threads with the same owner\nstring, where a concurrent thread inserts a new unconfirmed owner into\nthe hash between retry iterations. The window is narrow but repeatable\nunder adversarial conditions.\n\nFix by adding `goto retry` after `oo = NULL` so the already-allocated\n`new` is reused on the next iteration rather than overwritten.","publishedAt":"2026-07-19T12:01:57.261Z","updatedAt":"2026-10-19T20:07:46.251Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"c9aefb2b5f11337c9202c5bd0c45d71198449718","versionType":"git"},{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"017a6150106b054cc84d1b0582d97bd3a74d4281","versionType":"git"},{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"a10bf67fe06469a71a401f72f328237345d553c0","versionType":"git"},{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"57aee7a35bb12753057c5b65d72d1f46c0e95b07","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.10","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]}],"references":["https://git.kernel.org/stable/c/c9aefb2b5f11337c9202c5bd0c45d71198449718","https://git.kernel.org/stable/c/017a6150106b054cc84d1b0582d97bd3a74d4281","https://git.kernel.org/stable/c/a10bf67fe06469a71a401f72f328237345d553c0","https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07"],"weaknesses":["CWE-401"],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/53xxx/CVE-2026-53394.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53394","state":"PUBLISHED","datePublished":"2026-07-19T12:01:57.261Z","dateUpdated":"2026-10-19T20:07:46.251Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.402Z"},"containers":{"cna":{"title":"nfsd: avoid leaking pre-allocated openowner on unconfirmed retry race","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: avoid leaking pre-allocated openowner on unconfirmed retry race\n\nWhen find_or_alloc_open_stateowner() encounters an unconfirmed owner, it\ncalls release_openowner() and sets oo = NULL. Control then falls through\npast the `if (oo)` guard -- which would have freed any pre-allocated\n`new` -- and unconditionally executes `new = alloc_stateowner(...)`. If\n`new` was already allocated on a prior iteration, the pointer is\nsilently overwritten and the previous allocation (slab object + owner\nname buffer) is leaked.\n\nThis requires a race: two NFSv4.0 OPEN threads with the same owner\nstring, where a concurrent thread inserts a new unconfirmed owner into\nthe hash between retry iterations. The window is narrow but repeatable\nunder adversarial conditions.\n\nFix by adding `goto retry` after `oo = NULL` so the already-allocated\n`new` is reused on the next iteration rather than overwritten."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"c9aefb2b5f11337c9202c5bd0c45d71198449718","versionType":"git"},{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"017a6150106b054cc84d1b0582d97bd3a74d4281","versionType":"git"},{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"a10bf67fe06469a71a401f72f328237345d553c0","versionType":"git"},{"version":"23df17788c6212809848f836b10c4f85b16843a5","status":"affected","lessThan":"57aee7a35bb12753057c5b65d72d1f46c0e95b07","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.10","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.10","versionType":"semver"},{"version":"6.12.95","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.38","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.3","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/nfsd/nfs4state.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c9aefb2b5f11337c9202c5bd0c45d71198449718"},{"url":"https://git.kernel.org/stable/c/017a6150106b054cc84d1b0582d97bd3a74d4281"},{"url":"https://git.kernel.org/stable/c/a10bf67fe06469a71a401f72f328237345d553c0"},{"url":"https://git.kernel.org/stable/c/57aee7a35bb12753057c5b65d72d1f46c0e95b07"}],"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 - The flaw is in nfsd's NFSv4 OPEN handling, reachable remotely via NFS RPC on TCP/UDP port 2049 through svc_recv → NFSPROC4_COMPOUND → nfsd4_open → nfsd4_process_open1 → find_or_alloc_open_stateowner().\nAC:L - Exploitation requires a race between two NFSv4.0 OPEN requests with the same owner string, but the attacker controls both sides by issuing concurrent compounds from multiple connections; the fix commit itself states this is repeatable under adversarial conditions.\nPR:N - No local privileges on the server are required—only remote NFSv4 client access to establish a clientid (SETCLIENTID/CONFIRM) and send concurrent OPEN operations; the leak occurs in nfsd4_process_open1 before export/file permission checks complete.\nUI:N - Exploitation is fully automated via concurrent NFS protocol requests and requires no action from any victim user on the server or client side.\nS:U - Impact is confined to kernel memory consumption within nfsd's security authority; there is no cross-boundary escape to other components or privilege domains.\nC:N - This is a pure memory leak where orphaned slab objects lose all kernel references; no out-of-bounds read, use-after-free, or other mechanism exposes kernel data to the attacker.\nI:N - The bug silently drops a pointer to an allocated object without corrupting adjacent memory or providing any write or control-flow primitive—only heap memory is lost.\nA:H - Each successful race leaks a slab object plus an attacker-controlled owner-name buffer (up to NFS4_OPAQUE_LIMIT bytes), and the attack can be repeated indefinitely to cause unbounded kernel memory exhaustion, denying NFS service and potentially triggering system-wide OOM conditions."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T04:50:45.946Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.12.95"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"6.18.38"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"7.1.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.10","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-53394","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:30:18.446587Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-401","lang":"en","type":"CWE","description":"CWE-401 Missing Release of Memory after Effective Lifetime"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T20:07:46.251Z"}}]}}}