GHSA-w789-49fc-v8hr — high GitHub Advisory (CVE-2026-27818) in npm/terriajs-server

Description

A validation bug allows an attacker to proxy domains not explicitly allowed in the proxyableDomains configuration.

The validation only checks if a hostname ended with an allowed domain. This meant:

If example.com is allowed in proxyableDomains:

An attacker could register maliciousexample.com and proxy content through terriajs-server, bypassing proxy restrictions.

All versions up to 4.0.2 are affected. Upgrade to 4.0.3 to address the vulnerability.

Score	Percentile
0.10%	28.33%

Base score	Version	Severity	Vector
8.7	4.0	—	`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network. Attack complexity (AC:L) Exploitation conditions are straightforward and stable. Attack requirements (AT:N) No additional preconditions are required beyond normal reachability. Privileges required (PR:N) No privileges are required. User interaction (UI:N) No user interaction is required. Vulnerable system confidentiality impact (VC:N) No confidentiality impact on the vulnerable system. Vulnerable system integrity impact (VI:H) High integrity impact on the vulnerable system. Vulnerable system availability impact (VA:N) No availability impact on the vulnerable system. Subsequent system confidentiality impact (SC:N) No confidentiality impact on subsequent systems. Subsequent system integrity impact (SI:N) No integrity impact on subsequent systems. Subsequent system availability impact (SA:N) No availability impact on subsequent systems.

Type	Value
GHSA	GHSA-w789-49fc-v8hr ↗
CVE	CVE-2026-27818 ↗

CWE id	Name
CWE-20	Improper Input Validation
CWE-918	Server-Side Request Forgery (SSRF)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem	Package	Vulnerable range	First patched	Vulnerable functions
npm	terriajs-server	< 4.0.3	4.0.3	—