{"id":"CVE-2026-89714","title":"NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails\n\nnfs4_server_common_setup() allocates server->delegation_hash_table\nfirst, but server->destroy…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","cvssSource":"vendor","cwe":["CWE-772"],"vendor":"Linux","product":"Linux","affected":["Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < f3adf1643517357221422c05986d6de5df7b9913","Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < 0fd2b9687dae36be5b84eab39b4c627bb7ab33b3","Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < 2092f5b38f88be306140c77aeeeb43fc1adacacc","Linux 6.17"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:51:27.182Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89714","references":[{"url":"https://git.kernel.org/stable/c/f3adf1643517357221422c05986d6de5df7b9913"},{"url":"https://git.kernel.org/stable/c/0fd2b9687dae36be5b84eab39b4c627bb7ab33b3"},{"url":"https://git.kernel.org/stable/c/2092f5b38f88be306140c77aeeeb43fc1adacacc"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89714.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89714"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532288"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89714"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89714"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89714.mbox"}],"tags":["cve.org","csaf","vex","red-hat"],"epss":0.00206,"epssPercentile":0.10612,"ingestedAt":"2026-09-14T11:11:19.885Z","slug":"CVE-2026-89714","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nNFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails\n\nnfs4_server_common_setup() allocates server->delegation_hash_table\nfirst, but server->destroy - the only path that frees the table via\nnfs4_destroy_server() - is not assigned until the very end of the\nfunction. If any intermediate step fails (the is_ds_only_client()\ncheck, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),\nthe function returns with server->destroy still NULL, so the caller's\nnfs_free_server() skips the destroy callback and the hash table is\nleaked (4 KiB per attempt with the default delegation watermark).\n\nThis is trivially reachable from userspace: every failed NFSv4 mount\nleaks one allocation. A client that persistently retries a mount that\ncannot succeed leaks kernel memory without bound. Observed in\nproduction where a Longhorn backup poller retried mount.nfs4 against\nan NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of\nunreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated\n12 GiB of leaked slab before the source was identified via the\nkmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).\n\nReproducer:\n\n  # server exports NFSv3 only (or export path absent for v4)\n  while :; do mount -t nfs4 <server>:/missing /mnt; done\n  # watch SUnreclaim in /proc/meminfo grow 4 KiB per iteration\n\nFree the table on the error paths between the allocation and the\nassignment of server->destroy.\n\n## Affected\n\n- `Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < f3adf1643517357221422c05986d6de5df7b9913`\n- `Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < 0fd2b9687dae36be5b84eab39b4c627bb7ab33b3`\n- `Linux >= f5b3108e6a14418b120a3c38ca589b8d6cf87627 < 2092f5b38f88be306140c77aeeeb43fc1adacacc`\n- `Linux 6.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Vendor advisories\n\n- **Red Hat VEX** · Low · affected: Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat OpenShift Container Platform 4 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89714.json)","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":208941,"id":"CVE-2026-89714","ts":1790062296730,"field":"cvss","old":"7.5","new":"5.5"},{"seq":208940,"id":"CVE-2026-89714","ts":1790062296730,"field":"severity","old":"high","new":"medium"},{"seq":204029,"id":"CVE-2026-89714","ts":1789490231115,"field":"cvss","old":null,"new":"7.5"},{"seq":204028,"id":"CVE-2026-89714","ts":1789490231115,"field":"severity","old":"none","new":"high"},{"seq":147414,"id":"CVE-2026-89714","ts":1789270210816,"field":"cvss","old":null,"new":"7.5"},{"seq":147413,"id":"CVE-2026-89714","ts":1789270210816,"field":"severity","old":"none","new":"high"},{"seq":109172,"id":"CVE-2026-89714","ts":1789183730593,"field":"cvss","old":null,"new":"7.5"},{"seq":109171,"id":"CVE-2026-89714","ts":1789183730593,"field":"severity","old":"none","new":"high"}]}