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CVE-2026-55758: CC: Tweaked: Incomplete fix for GHSA-5jh9-2h63-pw4q: RFC 8215 NAT64 prefix (64:ff9b:1::/96) bypasses SSRF protection

• Severity: medium (CVSS 6.9 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-27 · updated 2026-09-09
• Weakness: CWE-918

Description

CC: Tweaked is a mod for Minecraft which adds programmable computers, turtles, and more to the game. Prior to 1.120.0, the SSRF protection in projects/core/src/main/java/dan200/computercraft/core/apis/http/options/AddressPredicate.java blocks the RFC 6052 64:ff9b::/96 NAT64 prefix but omits the RFC 8215 64:ff9b:1::/48 local-use prefix. On a dual-stack server using RFC 8215 NAT64, an unauthenticated user who can execute Lua code can use http.request or http.websocket with an address under 64:ff9b:1::/48 to reach loopback, RFC 1918, cloud metadata, or internal API endpoints because PrivatePattern.matches() does not classify the mapped IPv6 address as private. This issue is fixed in version 1.120.0.

Affected products

• CC-Tweaked: before 1.120.0

References

• https://github.com/cc-tweaked/CC-Tweaked/commit/d1bfb2571d3bde55529fac50d8303b7404499ec0
• https://github.com/cc-tweaked/CC-Tweaked/security/advisories/GHSA-2rrx-mch2-76cp
• https://github.com/cc-tweaked/CC-Tweaked/security/advisories/GHSA-2rrx-mch2-76cp

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