CVE-2026-55758 cc-tweaked CVE debrief

Who should care

Defenders of Minecraft servers using the CC: Tweaked mod, especially those with Lua code execution capabilities, should assess exposure and prioritize updating to version 1.120.0 or later.

Why it matters

CVE-2026-55758 is a medium-severity vulnerability in the CC: Tweaked mod for Minecraft that allows an unauthenticated user to execute Lua code and access internal endpoints. Defenders should prioritize updating to version 1.120.0 or later and restrict Lua code execution to trusted users.

• Potential access to internal API endpoints
• Possible exposure of cloud metadata
• Risk of unauthorized access to loopback interfaces
• Need for verification of affected versions and remediation

Technical summary

The vulnerability is caused by the SSRF protection in CC: Tweaked not properly blocking the RFC 8215 64:ff9b:1::/48 local-use prefix. This allows an attacker to access internal endpoints using http.request or http.websocket. The issue allows an unauthenticated user to execute Lua code and access loopback, RFC 1918, cloud metadata, or internal API endpoints on a dual-stack server using RFC 8215 NAT64. Defenders should prioritize updating to version 1.120.0 or later and restrict Lua code execution to trusted users. The vulnerability has a medium severity and defenders of Minecraft servers using the CC: Tweaked mod, especially those with Lua code execution capabilities, should assess exposure.

Defensive priority

Medium priority for defenders of Minecraft servers using the CC: Tweaked mod, especially those with Lua code execution capabilities.

Recommended defensive actions

• Review and update CC: Tweaked to version 1.120.0 or later
• Restrict Lua code execution to trusted users
• Monitor server logs for suspicious activity
• Implement additional security measures for internal API endpoints
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Evidence notes

The vulnerability is caused by the SSRF protection in CC: Tweaked not properly blocking the RFC 8215 64:ff9b:1::/48 local-use prefix. This allows an attacker to access internal endpoints using http.request or http.websocket.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.