# CVE-2026-74494: linux: In the Linux kernel, the following vulnerability has been resolved:  ksmbd: reject repeated SMB2 NEGOTIATE requests...

CVE-2026-74494 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-74494, released August 16, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-74494
- Priority: Routine
- CVSS: n/a
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 15, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  ksmbd: reject repeated SMB2 NEGOTIATE requests  Unauthenticated client can send multiple successful SMB2 NEGOTIATE requests on one connection before SESSION_SETUP. While the connection is in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation. Only the final allocation is freed when the connection is released, leaking one object for every additional successful request.  A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect without replying in this case. Set the connection exiting when rejecting the request, in addition to suppressing the response.  Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they update connection-wide dialect and negotiation state.  Move the locking contract to ksmbd_smb_negotiate_common(), where the state and dialect are selected, and add ksmbd_conn_new() for consistent state access.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.187-1 | [DEBIAN-CVE-2026-74494](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74494.md) | Aug 16, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.105-1 | [DEBIAN-CVE-2026-74494](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74494.md) | Aug 16, 2026 |
| Linux | linux Debian 14 | 7.1.8-1 | [DEBIAN-CVE-2026-74494](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74494.md) | Aug 16, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.107-1~deb12u1 | [DEBIAN-CVE-2026-74494](https://patchblox.com/security/data/fix/linux/debian-cve-2026-74494.md) | Aug 16, 2026 |

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Data as of 2026-11-09T07:25:28Z 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

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