TREK: SSRF Guard Bypass via IPv6 Transition Addresses (NAT64/6to4)

TREK is a collaborative travel planner. Prior to 3.4.0, the checkSsrf logic in server/src/utils/ssrfGuard.ts does not recognize NAT64, 6to4, or Teredo IPv6 transition addresses that encode an IPv4 destination. An authenticated user who controls a DNS record can supply a URL whose AAAA result is a transition address embedding a private, loopback, or link-local IPv4 target, and isAlwaysBlocked and isPrivateNetwork classify the address as allowed. In a deployment that routes the applicable transition format, user-facing imports, webhooks, integrations, or plugin egress can reach internal services or cloud metadata and expose returned information. This issue is fixed in version 3.4.0.

Source published

24 Sep 2026 18:09:31 UTC

Source modified

28 Sep 2026 14:51:56 UTC

Observed here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 6.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N