ksmbd: validate minimum PDU size for transform requests
Summary
| CVE | CVE-2026-68431 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-12 00:17:43 UTC |
| Updated | 2026-08-13 23:17:37 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 9.1 CRITICAL from 416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
EPSS: 0.002650000 probability, percentile 0.183920000 (date 2026-08-14)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | Secondary | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| 3.1 | CNA | DECLARED | 9.1 | CRITICAL | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 368ba06881c395f1c9a7ba22203cf8d78b4addc0 b62c510f59803f82f9b4c76ead2a56833b2984c7 git | Not specified |
| CNA | Linux | Linux | affected 368ba06881c395f1c9a7ba22203cf8d78b4addc0 cfc0b8e5080aec87700774e8568765eaa4b7b92b git | Not specified |
| CNA | Linux | Linux | affected df3a4518aee64f21bcafa891105b468413f27431 git | Not specified |
| CNA | Linux | Linux | affected 543c12c2644e772caa6880662c2a852cfdc5a10c git | Not specified |
| CNA | Linux | Linux | affected e9cb7be2fcbaee9e808b729e92948d38d52e5add git | Not specified |
| CNA | Linux | Linux | affected 5.15.145 5.16 semver | Not specified |
| CNA | Linux | Linux | affected 6.1.34 6.2 semver | Not specified |
| CNA | Linux | Linux | affected 6.3.8 6.4 semver | Not specified |
| CNA | Linux | Linux | affected 6.4 | Not specified |
| CNA | Linux | Linux | unaffected 6.4 semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.6 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2-rc5 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/b62c510f59803f82f9b4c76ead2a56833b2984c7 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/cfc0b8e5080aec87700774e8568765eaa4b7b92b | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.