{"id":"CVE-2026-90036","published":"2026-09-16T11:17:16.803","lastModified":"2026-09-21T14:17:27.843","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nNFSD: Prevent client use-after-free during blocked-lock reaping\n\nA bare lock owner -- its only remaining reference a blocked lock on\nnn->blocked_locks_lru -- holds a raw pointer to its nfs4_client but\nno reference keeping the client alive. When the per-net laundromat\nreaps such a lock, freeing the nbl drops the owner reference\nheld through flc_owner, and the final nfs4_put_stateowner()\ntakes the client's cl_lock. Because the laundromat detaches the\nnbl first, __destroy_client() no longer finds it, so a concurrent\nforce_expire_client() can free the client before nfs4_put_stateowner()\nruns, dereferencing cl_lock in freed memory.\n\nPin the client with cl_rpc_users before dropping\nnn->blocked_locks_lock, and skip clients already expiring, whose\nblocked locks __destroy_client() frees while holding an owner\nreference. Take nn->client_lock outside nn->blocked_locks_lock.\nEvery other site holds nn->blocked_locks_lock as a leaf, acquiring\nno further lock, so placing nn->client_lock outside it cannot form\na lock-order cycle.","cvssScore":9.8,"cvssSeverity":"CRITICAL","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/6fedb2eaff77554ca7a0deffd2e8bc0d6e8b38b0","tags":[]},{"url":"https://git.kernel.org/stable/c/7081224a59a0ca4edcd62c068588f4d900199a18","tags":[]},{"url":"https://git.kernel.org/stable/c/9026932ac8be4d0ae01db47f23619a98cc57b671","tags":[]},{"url":"https://git.kernel.org/stable/c/cd489b03587378645fe0d20142a33f1ed60bac98","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"This vulnerability allows a client to be freed prematurely during lock reaping, leading to potential use-after-free conditions and memory corruption.","exploitability":"Exploitation requires specific timing and concurrent operations, making it moderately difficult but not impossible.","blast_radius":"If exploited, this could lead to severe system instability or security breaches affecting the Linux kernel's integrity.","remediation":"Apply the latest kernel updates that address this vulnerability immediately.","tags":["kernel","use-after-free","memory-corruption","critical"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-09-23T08:45:07.985Z"}}