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.
References7
- git.kernel.org/stable/c/1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff
- git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0
- git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23
- git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06
- git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059
- git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a
- git.kernel.org/stable/c/a07dfb33112a42437f9d2d0bfd35c68575257381
Metrics
- CVSS 3.1
-
8.8
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 39 · as of 8 November 2026
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