{"id":"CVE-2026-68099","summary":"ksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: restore DACL size on check_add_overflow() to avoid malformed ACL\n\ncheck_add_overflow() unconditionally writes the truncated sum into *d\neven on overflow, per its contract in include/linux/overflow.h.\nThe four check_add_overflow() guards in set_posix_acl_entries_dacl()\nand set_ntacl_dacl() break out of the ACE-building loops on overflow,\nbut the truncated *size is then consumed downstream at the end of\nset_ntacl_dacl():\n\n    pndacl-\u003esize = cpu_to_le16(le16_to_cpu(pndacl-\u003esize) + size);\n\nThis produces an on-wire NT ACL whose pndacl-\u003esize under-reports the\nbytes actually written by the preceding fill_ace_for_sid()/memcpy()\ncalls, yielding a malformed ACL that can trigger out-of-bounds reads\nwhen re-parsed by clients or ksmbd itself.\n\nRestore *size to its pre-addition value on each overflow branch (via\n`*size -= ace_sz` / `size -= nt_ace_size`) so that after the break,\n*size once again holds the cumulative size of the successfully-written\nACEs. The committed ACL is then truncated-but-self-consistent rather\nthan malformed.\n\nThe ksmbd DACL builders are the only check_add_overflow() sites found\nwhere an overflow path breaks out of a loop and the destination value\nis consumed afterward. The other nearby break-style cases either\nreturn -EINVAL on overflow (transport_ipc.c) or break without\nconsuming the overflowed destination value afterward (buildid.c).","modified":"2026-10-28T02:30:49.284485436Z","published":"2026-08-10T11:58:13.940Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68099.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0bf38372821b1526f31538a7d9811844c55c7f38"},{"type":"WEB","url":"https://git.kernel.org/stable/c/847ecd4eb3c117c3d2f13f1e7ab506543aad8183"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8f3a7a499a7d9bb1c0f33fe78c4a4594d7e307f4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bbf0a8e931204ecdab494a88d43b0a24a04285c5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f4fcd0c1a243d449307b887fafee23921e9db5ab"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68099.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68099"},{"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":"41e53a773db6342ac9a689ee5ba635c31744c9f0"},{"fixed":"8f3a7a499a7d9bb1c0f33fe78c4a4594d7e307f4"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8d5729350b236896f51379588d9a690b7fafb8db"},{"fixed":"f4fcd0c1a243d449307b887fafee23921e9db5ab"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"e1955a94b6f17f4b058afa955a6f187eb3ed7615"},{"fixed":"0bf38372821b1526f31538a7d9811844c55c7f38"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43"},{"fixed":"847ecd4eb3c117c3d2f13f1e7ab506543aad8183"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"299f962c0b02d048fb45d248b4da493d03f3175d"},{"fixed":"bc90144ce8bb7fcf05ad9417c7adb4e9509d9e13"},{"fixed":"bbf0a8e931204ecdab494a88d43b0a24a04285c5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.1.175"},{"fixed":"6.1.184"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.6.136"},{"fixed":"6.6.148"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.12.84"},{"fixed":"6.12.101"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.18.25"},{"fixed":"6.18.42"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7.0.2"},{"fixed":"7.1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7"}]}],"versions":["v6.1.183","v6.1.182","v6.1.181","v6.1.180","v6.1.179","v6.1.178","v6.1.177","v6.1.176","v6.1.175","v6.6.147","v6.6.146","v6.6.145","v6.6.144","v6.6.143","v6.6.142","v6.6.141","v6.6.140","v6.6.139","v6.6.138","v6.6.137","v6.6.136","v6.12.100","v6.12.99","v6.12.98","v6.12.97","v6.12.96","v6.12.95","v6.12.94","v6.12.93","v6.12.92","v6.12.91","v6.12.90","v6.12.89","v6.12.88","v6.12.87","v6.12.86","v6.12.85","v6.12.84","v6.18.41","v6.18.40","v6.18.39","v6.18.38","v6.18.37","v6.18.36","v6.18.35","v6.18.34","v6.18.33","v6.18.32","v6.18.31","v6.18.30","v6.18.29","v6.18.28","v6.18.27","v6.18.26","v6.18.25","v7.0.14","v7.0.13","v7.0.12","v7.0.11","v7.0.10","v7.0.9","v7.0.8","v7.0.7","v7.0.6","v7.0.5","v7.0.4","v7.0.3","v7.0.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68099.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.184"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68099.json"}}],"schema_version":"1.9.2"}