{"id":"CVE-2026-99083","summary":"ksmbd: fix heap out-of-bounds write in krb5_authenticate()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work-\u003enext_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len \u003c= resp-\u003espnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work-\u003enext_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space.","modified":"2026-11-01T02:30:26.096588636Z","published":"2026-10-23T12:45:01.735Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99083.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff"},{"type":"WEB","url":"https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"},{"type":"WEB","url":"https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"},{"type":"WEB","url":"https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"},{"type":"WEB","url":"https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a07dfb33112a42437f9d2d0bfd35c68575257381"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/99xxx/CVE-2026-99083.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99083"},{"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":"676392184785ace61e939831e7ca44a03d438c3b"},{"fixed":"a07dfb33112a42437f9d2d0bfd35c68575257381"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"ef572ffa8eb44111eed2925fbb2adca78bdcbf61"},{"fixed":"1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8"},{"fixed":"59c6dcc5dd9dafe764ca0d40525933b2be69b059"},{"fixed":"80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"},{"fixed":"517404e157395d0f8da125ca956c566895dfcd06"},{"fixed":"4722d06b2907585074252061b1024a696c1cfc23"},{"fixed":"23a0be6a84a38ac169eeab49017934e8e27c65f0"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5.15.145"},{"fixed":"5.15.224"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.1.40"},{"fixed":"6.1.191"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.4.5"},{"fixed":"6.5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"2ba03cecb12ac7ac9e0170e251543c56832d9959"}]}],"versions":["v5.15.223","v5.15.222","v5.15.221","v5.15.220","v5.15.219","v5.15.218","v5.15.217","v5.15.216","v5.15.215","v5.15.214","v5.15.213","v5.15.212","v5.15.211","v5.15.210","v5.15.209","v5.15.208","v5.15.207","v5.15.206","v5.15.205","v5.15.204","v5.15.203","v5.15.202","v5.15.201","v5.15.200","v5.15.199","v5.15.198","v5.15.197","v5.15.196","v5.15.195","v5.15.194","v5.15.193","v5.15.192","v5.15.191","v5.15.190","v5.15.189","v5.15.188","v5.15.187","v5.15.186","v5.15.185","v5.15.184","v5.15.183","v5.15.182","v5.15.181","v5.15.180","v5.15.179","v5.15.178","v5.15.177","v5.15.176","v5.15.175","v5.15.174","v5.15.173","v5.15.172","v5.15.171","v5.15.170","v5.15.169","v5.15.168","v5.15.167","v5.15.166","v5.15.165","v5.15.164","v5.15.163","v5.15.162","v5.15.161","v5.15.160","v5.15.159","v5.15.158","v5.15.157","v5.15.156","v5.15.155","v5.15.154","v5.15.153","v5.15.152","v5.15.151","v5.15.150","v5.15.149","v5.15.148","v5.15.147","v5.15.146","v5.15.145","v6.1.190","v6.1.189","v6.1.188","v6.1.187","v6.1.186","v6.1.185","v6.1.184","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","v6.1.174","v6.1.173","v6.1.172","v6.1.171","v6.1.170","v6.1.169","v6.1.168","v6.1.167","v6.1.166","v6.1.165","v6.1.164","v6.1.163","v6.1.162","v6.1.161","v6.1.160","v6.1.159","v6.1.158","v6.1.157","v6.1.156","v6.1.155","v6.1.154","v6.1.153","v6.1.152","v6.1.151","v6.1.150","v6.1.149","v6.1.148","v6.1.147","v6.1.146","v6.1.145","v6.1.144","v6.1.143","v6.1.142","v6.1.141","v6.1.140","v6.1.139","v6.1.138","v6.1.137","v6.1.136","v6.1.135","v6.1.134","v6.1.133","v6.1.132","v6.1.131","v6.1.130","v6.1.129","v6.1.128","v6.1.127","v6.1.126","v6.1.125","v6.1.124","v6.1.123","v6.1.122","v6.1.121","v6.1.120","v6.1.119","v6.1.118","v6.1.117","v6.1.116","v6.1.115","v6.1.114","v6.1.113","v6.1.112","v6.1.111","v6.1.110","v6.1.109","v6.1.108","v6.1.107","v6.1.106","v6.1.105","v6.1.104","v6.1.103","v6.1.102","v6.1.101","v6.1.100","v6.1.99","v6.1.98","v6.1.97","v6.1.96","v6.1.95","v6.1.94","v6.1.93","v6.1.92","v6.1.91","v6.1.90","v6.1.89","v6.1.88","v6.1.87","v6.1.86","v6.1.85","v6.1.84","v6.1.83","v6.1.82","v6.1.81","v6.1.80","v6.1.79","v6.1.78","v6.1.77","v6.1.76","v6.1.75","v6.1.74","v6.1.73","v6.1.72","v6.1.71","v6.1.70","v6.1.69","v6.1.68","v6.1.67","v6.1.66","v6.1.65","v6.1.64","v6.1.63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