# CVE-2026-34227: Sliver One-Click Remote Access: Insecure CORS & Unauthenticated MCP Interface

> Unauthenticated attackers can hijack Sliver C2 sessions via a malicious link, enabling data exfiltration or infrastructure destruction through the operator's browser.

- **Severity:** Medium 5.9 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 31 Mar 2026
- **Updated:** 1 Apr 2026
- **Also known as:** GHSA-6fpf-248c-m7wm, GO-2026-5175

## What is CVE-2026-34227?

CVE-2026-34227 is a medium-severity missing authorization vulnerability in BishopFox sliver, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Sliver is a command and control framework that uses a custom Wireguard netstack. Prior to version 1.7.4, a single click on a malicious link gives an unauthenticated attacker immediate, silent control over every active C2 session or beacon, capable of exfiltrating all collected target data (e.g. SSH keys, ntds.dit) or destroying the entire compromised infrastructure, entirely through the operator's own browser. This issue has been patched in version 1.7.4.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains), CWE-306 (Missing Authentication for Critical Functionality)

## Which versions are affected by CVE-2026-34227?

3 open source packages ship an affected version, including github.com/bishopfox/sliver. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/bishopfox/sliver` | Go | All versions | 1.7.4 |
| `github.com/bishopfox/sliver` | Go | All versions | 1.7.4 |
| `github.com/bishopfox/sliver` | Go | All versions | 1.7.4 |

Products: Bishopfox Sliver.

## How do I fix CVE-2026-34227?

Upgrade github.com/bishopfox/sliver to 1.7.4 or later.

## Is CVE-2026-34227 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34227 exists.

Public exploit code:

- CVE-2026-34227 · CORS → CSRF chain on Sliver's unauthenticated MCP interface (github_poc): https://github.com/skoveit/CVE-2026-34227

## Other vulnerabilities in BishopFox sliver

- [CVE-2023-34758](https://insights.sbomify.com/CVE-2023-34758/): Silver vulnerable to MitM attack against implants due to a cryptography vulnerability (high 8.1)
- [CVE-2026-25791](https://insights.sbomify.com/CVE-2026-25791/): Sliver has a DNS C2 OTP Bypass Allows Unauthenticated Session Flooding and Denial of Service (high 7.5)
- [CVE-2025-27090](https://insights.sbomify.com/CVE-2025-27090/): Server-Side Request Forgery (SSRF) in sliver teamserver (medium 6.9)
- [CVE-2026-25760](https://insights.sbomify.com/CVE-2026-25760/): Website Path Traversal / Arbitrary File Read (Authenticated) in Sliver (medium 6.5)
- [CVE-2026-32941](https://insights.sbomify.com/CVE-2026-32941/): Sliver Vulnerable to Authenticated OOM via Memory Exhaustion in mTLS/WireGuard Transports (medium 5.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34227 and fix it if it is affected.

What it is: CVE-2026-34227 is a medium-severity missing authorization vulnerability in BishopFox sliver, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34227 exists.

Affected packages and fixed versions:
- github.com/bishopfox/sliver (Go): affected all versions; fixed in 1.7.4
- github.com/bishopfox/sliver (Go): affected all versions; fixed in 1.7.4
- github.com/bishopfox/sliver (Go): affected all versions; fixed in 1.7.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34227/ (Markdown: https://insights.sbomify.com/CVE-2026-34227/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34227
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34227
- OSV: https://osv.dev/vulnerability/CVE-2026-34227

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34227/
Summaries are generated and may contain mistakes; the official description above is the record.