Auth bypass in Bishopfox Sliver
CVE-2026-25791
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.
Vulnerability class: Broken Authentication
EPSS: 0.004 (33.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Bishopfox Sliver — versions < 1.7.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
- security-advisories@github.com (Product, x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-25791?
- CVE-2026-25791 is a high-severity vulnerability in Bishopfox Sliver, classified under Missing Authentication for Critical Function. CVSS score: 7.5/10. Published 2026-02-09.
- How severe is CVE-2026-25791?
- High severity. CVSS v3 base score is 7.5 out of 10.