# CVE-2026-42188: Geyser: Server-Side Request Forgery (SSRF) via Player Head Texture URL

> Attackers can force the Minecraft server to make arbitrary HTTP requests via crafted player head texture URLs, potentially accessing internal services.

- **Severity:** Low 2.4 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 11 May 2026
- **Updated:** 13 May 2026
- **Also known as:** GHSA-xcfg-fcr5-gw9r

## What is CVE-2026-42188?

CVE-2026-42188 is a low-severity server-side request forgery vulnerability in GeyserMC Geyser, published on 11 May 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Geyser is a bridge between Minecraft: Bedrock Edition and Minecraft: Java Edition. Prior to 2.9.3, a server-side request forgery (SSRF) vulnerability exists in Geyser’s handling of Bedrock player head texture data. By supplying a crafted Base64-encoded skin texture URL via the /give command, an attacker can cause the Minecraft server to issue arbitrary HTTP GET requests to attacker-controlled or internal endpoints. This occurs server-side, without proper URL validation, and can be triggered by a Bedrock client. This vulnerability is fixed in 2.9.3.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-42188?

2 open source packages ship an affected version, including org.geysermc.geyser:core. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.geysermc.geyser:core` | Maven | All versions | 2.9.3 |
| `org.geysermc.geyser:core` | Maven | All versions | 2.9.3 |

Products: Geysermc Geyser.

## How do I fix CVE-2026-42188?

Upgrade org.geysermc.geyser:core to 2.9.3 or later.

## Is CVE-2026-42188 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-42188 exists.

## Other vulnerabilities in GeyserMC Geyser

- [CVE-2021-39177](https://insights.sbomify.com/CVE-2021-39177/): User impersonation due to incorrect handling of the login JWT (high 7.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-42188 and fix it if it is affected.

What it is: CVE-2026-42188 is a low-severity server-side request forgery vulnerability in GeyserMC Geyser, published on 11 May 2026. An attacker needs administrator access to exploit it, 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-2026-42188 exists.

Affected packages and fixed versions:
- org.geysermc.geyser:core (Maven): affected all versions; fixed in 2.9.3
- org.geysermc.geyser:core (Maven): affected all versions; fixed in 2.9.3

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-2026-42188/ (Markdown: https://insights.sbomify.com/CVE-2026-42188/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42188
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42188
- OSV: https://osv.dev/vulnerability/CVE-2026-42188

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42188/
Summaries are generated and may contain mistakes; the official description above is the record.