CVE-2026-25791 HIGH

CVE-2026-25791: Sliver has a DNS C2 OTP Bypass Allows Unauthenticated Session Flooding and Denial of Service

Vendor Bishopfox
Product sliver
Weakness CWE-306 · Missing auth
Published February 9, 2026
Last update February 10, 2026
View on NVD All CVEs

CVSS base score

7.5/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Confidentiality None
Integrity None

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What the vulnerability does

01Description

Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to 1.7.0, the DNS C2 listener accepts unauthenticated TOTP bootstrap messages and allocates server-side DNS sessions without validating OTP values, even when EnforceOTP is enabled. Because sessions are stored without a cleanup/expiry path in this flow, an unauthenticated remote actor can repeatedly create sessions and drive memory exhaustion. This vulnerability is fixed in 1.7.0.

Key dates

02Disclosure timeline

February 9, 2026 CVE published
February 10, 2026 Record updated