{"id":"CVE-2026-89691","summary":"nfsd: clear opcnt on compound arg release to prevent OOB read","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: clear opcnt on compound arg release to prevent OOB read\n\nnfsd4_release_compoundargs() resets args-\u003eops to the inline iops[8]\narray when the dynamically-allocated ops buffer is freed, but leaves\nargs-\u003eopcnt at its original value (which can be up to 200 for NFSv4.1+\ncompounds).\n\nIf rq_status_counter is stuck at an odd value (which can happen when\nnfsd_dispatch() hits an error path after setting it odd), the RPC\nstatus dumpit handler reads min(opcnt, 16) entries from args-\u003eops[].\nSince iops only has 8 elements and is the last field in struct\nnfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory\nand leaks it to userspace via netlink.\n\nZero opcnt unconditionally in nfsd4_release_compoundargs() so stale\ncompound metadata is never exposed through the status interface.\n\n[ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]","modified":"2026-09-13T03:47:20.234019677Z","published":"2026-09-11T19:46:11.284Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89691.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/58bcdfb2b2e412088839ae740b1a95154dc0b8d0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c1a4f7b1848f95302df598217e1c7a1410c2d0c5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e879148867bd4c4cac42e063ffaffa187dddc6fe"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89691.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89691"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"bd9d6a3efa9709e653aafbeb859289feccb8e70c"},{"fixed":"58bcdfb2b2e412088839ae740b1a95154dc0b8d0"},{"fixed":"e879148867bd4c4cac42e063ffaffa187dddc6fe"},{"fixed":"c1a4f7b1848f95302df598217e1c7a1410c2d0c5"},{"fixed":"ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89691.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89691.json"}}],"schema_version":"1.9.0"}