CVE-2026-68431
Linux kernel vulnerability
- Published11 Aug 2026
Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate minimum PDU size for transform requests The receive path applies the minimum SMB2 PDU size check only when ProtocolId is SMB2_PROTO_NUMBER. A packet carrying SMB2_TRANSFORM_PROTO_NUM bypasses the check even when the negotiated dialect does not provide transform handling. On an SMB 2.1 connection, a short transform packet therefore reaches init_smb2_rsp_hdr(), which interprets the request as a full SMB2 header and reads beyond the request allocation. The copied fields can then be returned to the unauthenticated client. Compression transforms are converted to ordinary SMB2 messages before protocol validation. After that conversion, validate ordinary SMB2 requests against SMB2_MIN_SUPPORTED_PDU_SIZE and require encryption transform requests to contain both a transform header and an SMB2 header. This rejects truncated requests before work allocation.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HRemediation
No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.
References
- https://git.kernel.org/stable/c/22f1aa35b87e471cc31b35b74451f46630863b12
- https://git.kernel.org/stable/c/32e486b70c256d5ef4baa5a2936ade2fea50e8eb
- https://git.kernel.org/stable/c/928dda88d0e13fbca381255028f65b244343a4ea
- https://git.kernel.org/stable/c/b62c510f59803f82f9b4c76ead2a56833b2984c7
- https://git.kernel.org/stable/c/cfc0b8e5080aec87700774e8568765eaa4b7b92b
- https://git.kernel.org/stable/c/d8e5c5672724b8f3c4c099d2cf60239c996e5424
- https://git.kernel.org/stable/c/d9e9753dfd43bd27c956578df7804a3c90b80fdc
Frequently asked
Is CVE-2026-68431 being actively exploited?
CVE-2026-68431 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.50%.
How severe is CVE-2026-68431?
CVE-2026-68431 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.50% probability of exploitation.
How do I fix CVE-2026-68431?
Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-68431 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.