CVE-2025-38501

Published Aug 16, 2025

Last updated 3 months ago

CVSS high 7.5

Overview

AI description

Automated description summarized from trusted sources.

CVE-2025-38501 is a denial-of-service vulnerability in the Linux kernel's KSMBD (SMB Direct) implementation. It stems from the way KSMBD handles half-open TCP connections. An unauthenticated, remote attacker can exploit this by initiating numerous TCP connections to the KSMBD server but then failing to complete the handshake. The server continues to hold these incomplete connections, which exhausts the maximum connection limit and prevents legitimate SMB traffic. This vulnerability, dubbed "KSMBDrain," affects Linux kernel versions 5.3 onward. A proof-of-concept exploit demonstrates how an attacker can flood a server with SYN packets, causing the server to indefinitely hold sockets open. By repeatedly sending SYN packets, the attacker saturates the server's connection limit, effectively halting file transfers and authentication services. A patch has been implemented to limit repeated connections from the same IP address.

Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: limit repeated connections from clients with the same IP Repeated connections from clients with the same IP address may exhaust the max connections and prevent other normal client connections. This patch limit repeated connections from clients with the same IP.
Source
416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD status
Analyzed
Products
linux_kernel, debian_linux

Risk scores

CVSS 3.1

Type
Primary
Base score
7.5
Impact score
3.6
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity
HIGH

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-400

Social media

Hype score
Not currently trending

  1. LinuxカーネルのKSMBDに新たな脆弱性（CVE-2025-38501）が公開された。攻撃者が半開のTCP接続を量産してサーバーの接続上限を枯渇させ、SMBサービスを全面的に停止させる恐れがある。特にリモートから認証不要で

    @yousukezan

    17 Sept 2025

    3016 Impressions

    6 Retweets

    15 Likes

    7 Bookmarks

    0 Replies

    0 Quotes

  2. A new Linux kernel flaw, CVE-2025-38501, exposes KSMBD servers to unauthenticated remote DoS attacks. A public PoC is available now. #KSMBDrain #Linux #DoS #CVE #Vulnerability https://t.co/XEkBV3j9km

    @the_yellow_fall

    17 Sept 2025

    266 Impressions

    1 Retweet

    1 Like

    0 Bookmarks

    0 Replies

    0 Quotes

  3. CVE-2025-38501 Linux Kernel SMB Server Vulnerability https://t.co/f6KyKQxPUX

    @VulmonFeeds

    16 Aug 2025

    9 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

Configurations

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References

Sources include official advisories and independent security research.