What’s Vulnerable › Vulnerabilities

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

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-02-09 · updated 2026-06-17
• Weakness: CWE-306

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 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.

Affected products

• BishopFox sliver: before 1.7.0 — fixed in 1.7.0

How to fix

Upgrade to a fixed version: BishopFox sliver 1.7.0. Check the vendor advisory for mitigations.

References

• https://github.com/BishopFox/sliver/releases/tag/v1.7.0
• https://github.com/BishopFox/sliver/security/advisories/GHSA-wxrw-gvg8-fqjp

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