# CVE-2026-68431: linux: In the Linux kernel, the following vulnerability has been resolved:  ksmbd: validate minimum PDU size for transform r...

CVE-2026-68431 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-68431, released August 13, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-68431
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0037
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 12, 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.187-1 | [DEBIAN-CVE-2026-68431](https://patchblox.com/security/data/fix/linux/debian-cve-2026-68431.md) | Aug 13, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.105-1 | [DEBIAN-CVE-2026-68431](https://patchblox.com/security/data/fix/linux/debian-cve-2026-68431.md) | Aug 13, 2026 |
| Linux | linux Debian 14 | 7.1.6-1 | [DEBIAN-CVE-2026-68431](https://patchblox.com/security/data/fix/linux/debian-cve-2026-68431.md) | Aug 13, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.107-1~deb12u1 | [DEBIAN-CVE-2026-68431](https://patchblox.com/security/data/fix/linux/debian-cve-2026-68431.md) | Aug 13, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.