CVE-2026-85738 TREK: SSRF Guard Bypass via IPv6 Transition Addresses (NAT64/6to4)
Authenticated users can bypass SSRF protections using IPv6 transition addresses to access internal services or cloud metadata in TREK.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-85738?
CVE-2026-85738 is a medium-severity server-side request forgery vulnerability in liketrek TREK, published on 24 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-85738?
How do I fix CVE-2026-85738?
No fix has been published for CVE-2026-85738 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-85738 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-85738 exists.
Sources
Also known as GHSA-9hpq-mrpx-mcxg.