{"id":"CVE-2026-89712","title":"NFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock\n\nnfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with\nlist_for_each_entry_safe(ni, tmp, ...). …","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","cwe":["CWE-825"],"vendor":"Linux","product":"Linux","affected":["Linux >= a4bc287943f5695209ff36bdc89f17b48d68fae7 < 2b59029b8f24a99b5d844af2da3950d39d36eeea","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < d9e151fea5ed706c1284adacabd869b0be745db2","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 659ee3da073164e1e6e40dfcbc26eeed85845f93","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 60680ae7243b22de3d09be990d8e23bcfc4af837","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 77de363d9a1c8cd35f20482782c612cda085791a","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9","Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 036c1b182f4da65363e79ec0ac276edc6b7296e5","Linux >= 5.10.220 < 5.10.270","Linux 5.14"],"published":"2026-09-11","updated":"2026-10-19","sourceUpdated":"2026-10-19T08:51:25.202Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-89712","references":[{"url":"https://git.kernel.org/stable/c/2b59029b8f24a99b5d844af2da3950d39d36eeea"},{"url":"https://git.kernel.org/stable/c/d9e151fea5ed706c1284adacabd869b0be745db2"},{"url":"https://git.kernel.org/stable/c/659ee3da073164e1e6e40dfcbc26eeed85845f93"},{"url":"https://git.kernel.org/stable/c/60680ae7243b22de3d09be990d8e23bcfc4af837"},{"url":"https://git.kernel.org/stable/c/77de363d9a1c8cd35f20482782c612cda085791a"},{"url":"https://git.kernel.org/stable/c/4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8"},{"url":"https://git.kernel.org/stable/c/7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9"},{"url":"https://git.kernel.org/stable/c/036c1b182f4da65363e79ec0ac276edc6b7296e5"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89712.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-89712"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2532255"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89712"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89712"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89712.mbox"}],"tags":["cve.org","csaf","vex","red-hat","score-dispute"],"epss":0.00714,"epssPercentile":0.53475,"scores":{"cna":9.8,"vendor":7},"ingestedAt":"2026-09-14T15:23:07.449Z","slug":"CVE-2026-89712","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: restart ssc_expire_umount walk after dropping nfsd_ssc_lock\n\nnfsd4_ssc_expire_umount() walks nn->nfsd_ssc_mount_list with\nlist_for_each_entry_safe(ni, tmp, ...).  For each expired entry it\nsets nsui_busy = true, drops nfsd_ssc_lock to run mntput() on the\nsource vfsmount, then reacquires the lock to list_del + kfree the\nentry and continue iterating via the macro's saved tmp pointer.\n\nThe nsui_busy flag protects the current ni from concurrent\nnfsd4_ssc_setup_dul() finders during the lock-drop window, but it\ndoes not pin tmp.  Another nfsd RPC thread that fails its source-\nserver mount and reaches nfsd4_ssc_cancel_dul() will, during that\nsame window, take nfsd_ssc_lock, list_del + kfree its own ssc_umount\nitem, and release the lock.  If that item is the saved tmp of the\nexpire walk, the next iteration dereferences a freed\nnfsd4_ssc_umount_item.\n\nRestart the walk from the head after the mntput() unlock window so\nno saved next pointer survives the lock-drop.  The list is bounded\nby the number of active inter-server source mounts (typically small)\nand the expire delayed-work runs periodically rather than per-IO,\nso the restart is cheap.\n\n## Affected\n\n- `Linux >= a4bc287943f5695209ff36bdc89f17b48d68fae7 < 2b59029b8f24a99b5d844af2da3950d39d36eeea`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < d9e151fea5ed706c1284adacabd869b0be745db2`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 659ee3da073164e1e6e40dfcbc26eeed85845f93`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 60680ae7243b22de3d09be990d8e23bcfc4af837`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 77de363d9a1c8cd35f20482782c612cda085791a`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 4ed8d2317aef21cc2a9e5a55d6b59860b4b151a8`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 7377fa964b8aaf47cb04e5efcc4c82d15e8c2ce9`\n- `Linux >= f4e44b393389c77958f7c58bf4415032b4cda15b < 036c1b182f4da65363e79ec0ac276edc6b7296e5`\n- `Linux >= 5.10.220 < 5.10.270`\n- `Linux 5.14`\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** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89712.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":224602,"id":"CVE-2026-89712","ts":1792401432313,"field":"cvss","old":"7","new":"9.8"},{"seq":224601,"id":"CVE-2026-89712","ts":1792401432313,"field":"severity","old":"high","new":"critical"},{"seq":208450,"id":"CVE-2026-89712","ts":1790005705018,"field":"cvss","old":"9.8","new":"7"},{"seq":208449,"id":"CVE-2026-89712","ts":1790005705018,"field":"severity","old":"critical","new":"high"},{"seq":197706,"id":"CVE-2026-89712","ts":1789384318487,"field":"cvss","old":"5.3","new":"9.8"},{"seq":197705,"id":"CVE-2026-89712","ts":1789384318487,"field":"severity","old":"medium","new":"critical"},{"seq":183655,"id":"CVE-2026-89712","ts":1789356676736,"field":"cvss","old":"9.8","new":"5.3"},{"seq":183654,"id":"CVE-2026-89712","ts":1789356676736,"field":"severity","old":"critical","new":"medium"},{"seq":153602,"id":"CVE-2026-89712","ts":1789285351452,"field":"cvss","old":null,"new":"9.8"},{"seq":153601,"id":"CVE-2026-89712","ts":1789285351452,"field":"severity","old":"none","new":"critical"},{"seq":147572,"id":"CVE-2026-89712","ts":1789270211435,"field":"cvss","old":null,"new":"5.3"},{"seq":147571,"id":"CVE-2026-89712","ts":1789270211435,"field":"severity","old":"none","new":"medium"},{"seq":109324,"id":"CVE-2026-89712","ts":1789183731429,"field":"cvss","old":null,"new":"5.3"},{"seq":109323,"id":"CVE-2026-89712","ts":1789183731429,"field":"severity","old":"none","new":"medium"}]}