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Fencer Intel
medium 6.3

CVE-2026-85738 json

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

published 3mo ago modified last mo. also EUVD-2026-86342 , GHSA-9hpq-mrpx-mcxg

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository liketrek/TREK. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

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 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.

Patch / fix

  • liketrek trek 3.4.0

Is CVE-2026-85738 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.39% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/liketrek/TREK/security/advisories/GHSA-9hpq-mrpx-mcxg referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Affected products

  • liketrek TREK

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of liketrek/TREK published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.