{"id":"CVE-2026-89656","summary":"libceph: reject buckets with mismatched CRUSH ids","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nlibceph: reject buckets with mismatched CRUSH ids\n\ncrush_decode() stores bucket data by array slot, and the mapper later\nderives the per-bucket workspace index from the decoded bucket id. A\nmalformed map can therefore make one bucket reuse another bucket's\nworkspace by encoding an id different from -1 - slot.\n\nFor uniform buckets, the second replica selection expands the source\nbucket's permutation into that aliased workspace buffer. If the source\nbucket is larger than the aliased bucket, the write runs past the smaller\npermutation array and can escape the kvmalloc'd CRUSH workspace. KASAN\nreports a slab OOB write of 4 bytes in bucket_perm_choose().\n\nReject buckets whose encoded id does not match their array slot. Valid\nCRUSH maps already use the canonical negative id corresponding to the\nbucket slot, so this restores the invariant expected by\nwork-\u003ework[-1 - in-\u003eid] without changing valid map behavior.","modified":"2026-09-12T11:47:14.740836172Z","published":"2026-09-11T19:45:45.483Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89656.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/00562ccd4e88d092b9b851df50fad20442bfeb24"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3516a4131c4e45d62ee4e42e82c36930e8c1fbbd"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3cde4a8302301679937474a5f7a851394cc1bd11"},{"type":"WEB","url":"https://git.kernel.org/stable/c/79900d978158b2d80eef952fc41b9e4dc58d7b83"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89656.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89656"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"66a0e2d579dbec5c676cfe446234ffebb267c564"},{"fixed":"3516a4131c4e45d62ee4e42e82c36930e8c1fbbd"},{"fixed":"00562ccd4e88d092b9b851df50fad20442bfeb24"},{"fixed":"79900d978158b2d80eef952fc41b9e4dc58d7b83"},{"fixed":"3cde4a8302301679937474a5f7a851394cc1bd11"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89656.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.11.0"},{"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-2026-89656.json"}}],"schema_version":"1.9.0"}