{"id":"CVE-2026-99110","title":"smb: client: fix heap overflow in cifs_do_set_acl()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in cifs_do_set_acl()\n\ncifs_set_acl() validates ACL size using posix_acl_xattr_size():\n\n        4 + (count * 8)  // 4-byte header + 8 byte…","severity":"high","cvss":7,"cvssVector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 68652afb9b9adf70125971abee9b95341e042249","Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 9312a00215602ba028495ef3fa00fb84af0478e0","Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < d96f3365ce61c5f39602955af43c8174548dee98","Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 596b4062e6c75bdd85a7f2b7f2087a872dc420ac","Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 1dac61e2c29d1a71784604b48cf3b1234a65ec29","Linux 6.2"],"published":"2026-10-28","updated":"2026-10-31","sourceUpdated":"2026-10-31T12:43:03.377Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99110","references":[{"url":"https://git.kernel.org/stable/c/68652afb9b9adf70125971abee9b95341e042249"},{"url":"https://git.kernel.org/stable/c/9312a00215602ba028495ef3fa00fb84af0478e0"},{"url":"https://git.kernel.org/stable/c/d96f3365ce61c5f39602955af43c8174548dee98"},{"url":"https://git.kernel.org/stable/c/596b4062e6c75bdd85a7f2b7f2087a872dc420ac"},{"url":"https://git.kernel.org/stable/c/1dac61e2c29d1a71784604b48cf3b1234a65ec29"}],"tags":["cve.org"],"epss":0.00134,"epssPercentile":0.02959,"ingestedAt":"2026-10-28T11:09:40.454Z","slug":"CVE-2026-99110","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix heap overflow in cifs_do_set_acl()\n\ncifs_set_acl() validates ACL size using posix_acl_xattr_size():\n\n        4 + (count * 8)  // 4-byte header + 8 bytes per ACE\n\ncifs_do_set_acl() then calls posix_acl_to_cifs() to write the CIFS\nwire format into the same buffer:\n\n        6 + (count * 10)  // 6-byte header + 10 bytes per ACE\n\nAn ACL that passes the xattr-based check in cifs_set_acl() can\noverflow the heap when posix_acl_to_cifs() writes the larger CIFS\nformat.\n\nValidate the CIFS format size against the remaining buffer space and\nUSHRT_MAX before converting--data_count is __u16, so sizes above\nUSHRT_MAX truncate the on-wire packet length, causing the server to\napply a partial ACL.  Replace MaxDataCount = 1000 with\nmin(CIFSMaxBufSize, USHRT_MAX).\n\n## Affected\n\n- `Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 68652afb9b9adf70125971abee9b95341e042249`\n- `Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 9312a00215602ba028495ef3fa00fb84af0478e0`\n- `Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < d96f3365ce61c5f39602955af43c8174548dee98`\n- `Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 596b4062e6c75bdd85a7f2b7f2087a872dc420ac`\n- `Linux >= dc1af4c4b4721abfa07b351063825acc7e69cc66 < 1dac61e2c29d1a71784604b48cf3b1234a65ec29`\n- `Linux 6.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":39,"depthScoreParts":{"impact":38.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":233302,"id":"CVE-2026-99110","ts":1793896011655,"field":"cvss","old":null,"new":"7"},{"seq":233301,"id":"CVE-2026-99110","ts":1793896011655,"field":"severity","old":"none","new":"high"}]}