---
id: "CVE-2026-99278"
page: "https://infrastack.ai/live/CVE-2026-99278"
kind: "vulnerability"
aliases: ["CVE-2026-99278"]
title: "Linux kernel ksmbd: a client can keep unlimited SMB sessions open"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["file-server", "ksmbd", "linux-kernel", "runtime", "smb"]
not_affected_if: ["ksmbd-not-loaded", "samba-only"]
published_at: "2026-11-07T14:17:03+00:00"
first_seen_at: "2026-11-07T14:47:40+00:00"
updated_at: "2026-11-07T14:49:51+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99278", "first_seen_at": "2026-11-07T14:47:40+00:00"}]
exploit_sources: []
---

# Linux kernel ksmbd: a client can keep unlimited SMB sessions open

Link for people: https://infrastack.ai/live/CVE-2026-99278 (this .md is for agents)

The ksmbd SMB server in the Linux kernel does not cap how many authenticated sessions one connection can hold, because the pending limit only counts sessions still being set up. A remote client that authenticates repeatedly on one connection can exhaust server memory and resources.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the kernel version with `uname -r` and whether the ksmbd module is loaded with `lsmod | grep ksmbd`
- Look for a configured `max_sessions_per_connection` setting in the ksmbd startup configuration

## Timeline

- 2026-11-07T14:47:40+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99278

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: limit sessions on each connection

The pending setup limit only counts InProgress sessions. A client can
complete authentication repeatedly and retain an unbounded number of Valid
sessions on one connection.

Reserve a connection slot before allocating a session and retain a
connection reference while authentication is in progress. The first SMB3
channel takes over that reservation; binding to another connection reserves
one slot there. Reauthentication and authentication continuation reuse the
existing reservation. Return slots on allocation or insertion failure,
channel removal, and final session destruction.

Accept max_sessions_per_connection in reserved startup-request space and
default to 64 when older tools leave it zero. Keep the request size and
existing field offsets unchanged. Expose the configured limit in procfs.
The existing connection limits bound the aggregate number of sessions
without a separate global session allocation limit.

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_