---
id: CVE-2026-85738
title: TREK is a collaborative travel planner
summary: >-
  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 c…
severity: medium
cvss: 6.3
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N'
cwe:
  - CWE-918
vendor: liketrek
product: TREK
affected:
  - TREK < 3.4.0
published: '2026-09-24'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T13:17:26.220'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-85738'
references:
  - url: >-
      https://github.com/liketrek/TREK/commit/a2bd9be184a94997105ce190dad920c41e7b10df
    label: security-advisories@github.com
  - url: 'https://github.com/liketrek/TREK/pull/1540'
    label: security-advisories@github.com
  - url: 'https://github.com/liketrek/TREK/releases/tag/v3.4.0'
    label: security-advisories@github.com
  - url: 'https://github.com/liketrek/TREK/security/advisories/GHSA-9hpq-mrpx-mcxg'
    label: security-advisories@github.com
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T18:49:36.724Z'
epss: 0.00303
epssPercentile: 0.20538
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.