TREK: SSRF Guard Bypass via IPv6 Transition Addresses (NAT64/6to4) (CVE-2026-85738) | HOL Guard CVE

Medium · CVSS 6.3CVE-2026-85738

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

Answer in brief

CVE-2026-85738 records a Medium severity (CVSS 6.3) vulnerability in TREK: SSRF Guard Bypass via IPv6 Transition Addresses (NAT64/6to4). The current sources do not mark it as known exploited. The current feed maps liketrek/TREK (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 24, 2026Updated Sep 24, 2026Source checked Sep 25, 2026First seen by HOL Sep 25, 2026Material review Sep 24, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 6.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 6.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps liketrek/TREK (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
liketrek/TREKgeneric	<3.4.0	3.4.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for liketrek/TREK.
Review the reported fix. Update liketrek/TREK to 3.4.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 25, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.