GHSA-2J87-48P3-J5XW
Vulnerability from github – Published: 2026-10-23 15:31 – Updated: 2026-10-24 15:32In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix heap out-of-bounds write in krb5_authenticate()
In krb5_authenticate(), out_len is calculated to determine available headroom in response_buf for the incoming Kerberos AP-REP token. However, when SMB2_SESSION_SETUP is processed as a non-first element of a compounded SMB2 request, the calculation omits work->next_smb2_rsp_hdr_off.
This causes out_len to overstate remaining buffer headroom by the cumulative size of prior responses in the compound chain. Consequently, the length check in ksmbd_krb5_authenticate() (*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy() to write the AP-REP blob past the end of response_buf into adjacent kernel heap memory.
Fix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len, ensuring it accurately reflects physical remaining buffer space.
{
"affected": [],
"aliases": [
"CVE-2026-99083"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-23T13:17:32Z",
"severity": "HIGH"
},
"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.",
"id": "GHSA-2j87-48p3-j5xw",
"modified": "2026-10-24T15:32:51Z",
"published": "2026-10-23T15:31:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99083"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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