CVE-2026-25791
Published: 09 February 2026
Summary
CVE-2026-25791 is a high-severity Missing Authentication for Critical Function (CWE-306) vulnerability in Bishopfox Sliver. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 8.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Limiting concurrent sessions directly prevents uncontrolled resource consumption by capping the number of active sessions per user or account.
Requires established identification and authentication to unlock, mitigating missing authentication for continued system access.
Requiring identification and rationale for actions allowed without authentication ensures critical functions are not left unprotected by forcing review of authentication requirements.
Authorizing mobile device connections to organizational systems ensures authentication is performed for this critical access function.
Guarantees critical functions are protected by mandatory invocation of the access control mechanism.
Auditing sessions makes it possible to detect access to critical functions without required authentication.
Analysis identifies uncontrolled resource consumption indicative of denial-of-service or abuse attempts.
The assessment process confirms authentication is present and effective for critical functions, preventing exploitation from missing authentication.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Unauthenticated remote exploitation of the public DNS C2 listener via repeated bootstrap messages exhausts server resources, directly enabling T1190 (public-facing application exploitation) and T1499.002 (service exhaustion flood for DoS).
NVD Description
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…
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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.
Deeper analysisAI
CVE-2026-25791 is a vulnerability in the Sliver command and control (C2) framework, which uses a custom Wireguard netstack. Prior to version 1.7.0, the DNS C2 listener accepts unauthenticated TOTP bootstrap messages and allocates server-side DNS sessions without validating OTP values, even when the EnforceOTP option is enabled. These sessions are stored without a cleanup or expiry mechanism, allowing resource exhaustion.
An unauthenticated remote actor can exploit this vulnerability by repeatedly sending bootstrap messages to create numerous sessions, resulting in memory exhaustion and denial of service. The CVSS v3.1 base score is 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), reflecting high availability impact with low attack complexity and no privileges required. It maps to CWE-306 (Missing Authentication for Critical Function) and CWE-400 (Uncontrolled Resource Consumption).
The vulnerability is addressed in Sliver version 1.7.0. Additional details are available in the release notes at https://github.com/BishopFox/sliver/releases/tag/v1.7.0 and the security advisory at https://github.com/BishopFox/sliver/security/advisories/GHSA-wxrw-gvg8-fqjp.
Details
- CWE(s)