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

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-05-11 · updated 2026-10-26
Weakness: CWE-918

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.

Affected products

GeyserMC Geyser: before 2.9.3 — fixed in 2.9.3

How to fix

Upgrade to a fixed version: GeyserMC Geyser 2.9.3. Check the vendor advisory for mitigations.

References

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