CVE-2026-99083
Received
Received - Intake
Heap Out-of-Bounds Write in ksmbd Linux Kernel
Vulnerability report for CVE-2026-99083, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-23
Last updated on: 2026-10-23
Assigner: kernel.org
Description
Description
In 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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 |
| Linux | Linux | 0 |
| Linux | Linux | 0 |
| Linux | Linux | 0 |
| Linux | Linux | 0 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
