{"id":"CVE-2026-97555","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in DACL owner/group rewrite\n\nWhen id_mode_to_cifs_acl rewrites an existing DACL, it allocates a\nbuffer sized according to the on-disk DAC…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in DACL owner/group rewrite\n\nWhen id_mode_to_cifs_acl rewrites an existing DACL, it allocates a\nbuffer sized according to the on-disk DAC…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cwe":["CWE-787"],"vendor":"Linux","product":"Linux","affected":["Linux >= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 < d5cea6766ae1868a51c7d17d77d065b4f55c587f","Linux >= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 < fb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1","Linux >= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 < 7fa84c9ca690643f429ae2709584a47e74b572c9","Linux >= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 < 2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd","Linux >= bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 < 0ee150794c75bcd0be0e24ff3394f433cbae18cc","Linux 5.12"],"published":"2026-09-25","updated":"2026-10-03","sourceUpdated":"2026-10-03T11:18:03.187","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-97555","references":[{"url":"https://git.kernel.org/stable/c/0ee150794c75bcd0be0e24ff3394f433cbae18cc","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2a9aee9ef5622d58d8aafaa3263b3ffe70e2d9dd","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7fa84c9ca690643f429ae2709584a47e74b572c9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d5cea6766ae1868a51c7d17d77d065b4f55c587f","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fb736ab4fb8c4fdb8b2f9ccd3a62e03d11549ca1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97555.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-97555"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2541166"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-97555"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97555"},{"url":"https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-97555.mbox"}],"tags":["nvd","cve.org","csaf","vex","red-hat"],"epss":0.00531,"epssPercentile":0.44716,"scores":{"nvd":8.8,"vendor":7,"cna":8.8},"ingestedAt":"2026-09-25T11:06:38.916Z","slug":"CVE-2026-97555","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in DACL owner/group rewrite\n\nWhen id_mode_to_cifs_acl rewrites an existing DACL, it allocates a\nbuffer sized according to the on-disk DACL length reported by\ndacl_ptr->size. However, replace_sids_and_copy_aces may rewrite each\nACE with a new owner/group SID obtained from the cifs.idmap upcall.\nThose SIDs can have up to SID_MAX_SUB_AUTHORITIES (15) sub-authorities,\nmaking each ACE up to 76 bytes (sizeof(struct smb_ace)).\n\nIf the original DACL contains short SIDs (e.g., 1 sub-authority) while\nthe replacement SIDs are long, the rewritten ACEs overflow the\nallocation.\n\nFix this by always budgeting for worst-case SID expansion: allocate\nsizeof(struct smb_acl) plus num_aces * sizeof(struct smb_ace), which\ncovers the smb_acl header and room for every ACE at maximum SID size.\nThis replaces the previous split logic that used dacl_ptr->size for\ncifsacl mounts but num_aces * sizeof(struct smb_ace) for mode_from_sid\nmounts: both paths can trigger the same rewrite and need the same\nheadroom.\n\nKASAN reports this as:\n  BUG: KASAN: slab-out-of-bounds in build_sec_desc+0x1e8a/0x2680 [cifs]\n  Write of size 4 at addr ffff8881a5e25374 by task chown/5298\n  ...\n  The buggy address is located 0 bytes to the right of\n   allocated 884-byte region [ffff8881a5e25000, ffff8881a5e25374)\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 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · updated 2026-09-29 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-97555.json)","depth":"twilight","depthScore":49,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":211002,"id":"CVE-2026-97555","ts":1790349122863,"field":"cvss","old":null,"new":"8.8"},{"seq":211001,"id":"CVE-2026-97555","ts":1790349122863,"field":"severity","old":"none","new":"high"}]}