CVE-2026-68431ksmbd: validate minimum PDU size for transform requests
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No exploitation reported and no EPSS estimate yet.
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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
- 9.1 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Aug 23, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from df3a4518aee64f21bcafa891105b468413f27431 before 22f1aa35b87e471cc31b35b74451f46630863b12; from 543c12c2644e772caa6880662c2a852cfdc5a10c before 928dda88d0e13fbca381255028f65b244343a4ea; from 368ba06881c395f1c9a7ba22203cf8d78b4addc0 before d8e5c5672724b8f3c4c099d2cf60239c996e5424; 368ba06881c395f1c9a7ba22203cf8d78b4addc0 builds before 32e486b70c256d5ef4baa5a2936ade2fea50e8eb; from 368ba06881c395f1c9a7ba22203cf8d78b4addc0 before d9e9753dfd43bd27c956578df7804a3c90b80fdc; from 368ba06881c395f1c9a7ba22203cf8d78b4addc0 before b62c510f59803f82f9b4c76ead2a56833b2984c7; from 368ba06881c395f1c9a7ba22203cf8d78b4addc0 before cfc0b8e5080aec87700774e8568765eaa4b7b92b; e9cb7be2fcbaee9e808b729e92948d38d52e5add; and 3 more ranges | CNA record |
References
- https://git.kernel.org/stable/c/22f1aa35b87e471cc31b35b74451f46630863b12
- https://git.kernel.org/stable/c/928dda88d0e13fbca381255028f65b244343a4ea
- https://git.kernel.org/stable/c/d8e5c5672724b8f3c4c099d2cf60239c996e5424
- https://git.kernel.org/stable/c/32e486b70c256d5ef4baa5a2936ade2fea50e8eb
- https://git.kernel.org/stable/c/d9e9753dfd43bd27c956578df7804a3c90b80fdc
- https://git.kernel.org/stable/c/b62c510f59803f82f9b4c76ead2a56833b2984c7
- https://git.kernel.org/stable/c/cfc0b8e5080aec87700774e8568765eaa4b7b92b
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.