Geysermc Geyser
CVE-2026-42188
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.
What this means for your business
- It affects Geysermc Geyser. It matters if your company, or a supplier that handles your data, runs it.
- Code showing how to exploit it has been published, but real attacks have not been confirmed.
- An attacker can use it remotely, over a network, with an administrator login, but only after tricking someone into an action such as opening a file or a link.
What to do
- 1Check whether your company or your suppliers run Geysermc Geyser, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
Not sure if your company is exposed?
Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.
Scoring
- CVSS
- 2.4 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:L/I:N/A:N- Weakness
- CWE-918
- Assigned by
- security-advisories@github.com
Dates
- Published
- 2026-05-11
- Last modified
- 2026-08-25
- Sources
- NVD
Affected products
- Geysermc Geyser- 2.9.3
As listed in the NVD configuration data. Not a statement about your estate.