# CVE-2026-34227: BishopFox Sliver unauthenticated remote access in MCP interface

Source: https://junglewise.ai/threats/cve-2026-34227-bishopfox-sliver-unauthenticated-remote-access-in-mcp-interface  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-31. Updated: 2026-07-24  
License: CC BY 4.0 with a link back

CVE-2026-34227 · Severity: high · CVSS 8.8 · Published 2026-03-31

Sliver is a command and control (C2) framework used by security professionals to manage simulated cyberattacks. A vulnerability in its management interface allows an attacker to take over active sessions if an operator clicks a malicious link. This could result in the theft of sensitive data like SSH keys or the complete destruction of the testing infrastructure.

Technologies: [Bishopfox Sliver](https://junglewise.ai/threats/technologies/sliver), [github.com/bishopfox/sliver (Go)](https://junglewise.ai/threats/technologies/github-com-bishopfox-sliver). Vendors: [Bishopfox](https://junglewise.ai/threats/vendors/bishopfox), [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-34227 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-34227 being exploited in the wild.

**How severe is CVE-2026-34227?** High severity, with a CVSS score of 8.8, published 31 March 2026.

**Which products and versions are affected?** Bishopfox Sliver < 1.7.4; github.com/bishopfox/sliver (Go) SEMVER:introduced=0,fixed=1.7.4.

**Is there a fix for CVE-2026-34227?** Yes. github.com/bishopfox/sliver (Go): upgrade to 1.7.4 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-34227 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-34227?** Check whether you run Bishopfox Sliver or github.com/bishopfox/sliver (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/bishopfox/sliver (Go): upgrade to 1.7.4 or later

  ```sh
  go get github.com/bishopfox/sliver@v1.7.4
  ```


## Technical details

The Sliver MCP (Multi-Client Protocol) server, which typically binds to localhost:8080, lacks authentication and implements a permissive CORS policy (Access-Control-Allow-Origin: *). Because the server fails to validate the Content-Type header, attackers can use 'Simple Requests' to bypass CORS preflight checks. An attacker can use Cross-Site Request Forgery (CSRF) via a malicious website to execute commands through the operator's browser, such as listing sessions, reading files (fs_cat), or deleting files (fs_rm). If the interface is misconfigured to bind to 0.0.0.0, it becomes directly accessible over the network without user interaction. The issue is patched in version 1.7.4.

## Affected products

- BishopFox Sliver < 1.7.4

## Identifiers

- CVE-2026-34227
- GHSA-6fpf-248c-m7wm
- GO-2026-5175

## Timeline

- 2026-03-30: advisory: GitHub/Vendor advisory published
- 2026-03-31: disclosed: NVD publication date
- 2026-03-31: patched: Fixed in version 1.7.4

## References

- [https://github.com/BishopFox/sliver/security/advisories/GHSA-6fpf-248c-m7wm](https://github.com/BishopFox/sliver/security/advisories/GHSA-6fpf-248c-m7wm)

## Related threats

- [Sliver unauthenticated memory exhaustion in HTTP(S) listener](https://junglewise.ai/threats/cve-2026-77622-sliver-unauthenticated-memory-exhaustion-denial-of-service-in)
- [BishopFox Sliver unhandled panic in operator gRPC handler](https://junglewise.ai/threats/cve-2026-102507-sliver-c2-framework-version-1-7-7-and-earlier-contains-an)
- [GO-2026-4899 - Sliver: Nil Pointer Dereference in tunnelCloseHandler causes panic when a reverse tunnel (rportfwd)…](https://junglewise.ai/threats/go-2026-4899-sliver-nil-pointer-dereference-in-tunnelclosehandler-bd83eea8)
- [Sliver: Nil Pointer Dereference in tunnelCloseHandler causes panic when a reverse tunnel (rportfwd) close is attempted](https://junglewise.ai/threats/sliver-nil-pointer-dereference-in-tunnelclosehandler-causes-panic-when-df5d6c15)
- [Sliver Vulnerable to Authenticated OOM via Memory Exhaustion in mTLS/WireGuard Transports](https://junglewise.ai/threats/cve-2026-32941-sliver-vulnerable-to-authenticated-oom-via-memory-exhaustion-in)