CVE-2026-27818: Terriajs server TerriaJS-Server Has A Domain Validation Vulnerability

HIGH
Advisory Identifier: GHSA-w789-49fc-v8hr
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CWE-20 CWE-918
Published
Advisory Summary

CVE-2026-27818 is a HIGH terriajs-server has a domain validation vulnerability (CWE-20: Improper Input Validation) affecting Terriajs server libraries in the npm ecosystem. The issue involves terriajs-server has a domain validation bypass vulnerability in its proxy allowlist. Remediation is available by upgrading affected packages to version 4.0.3.

CVE-2026-27818 at a Glance

CVE Identifier CVE-2026-27818
GHSA Identifier GHSA-w789-49fc-v8hr
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-20: Improper Input Validation
Affected Product Terriajs server
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-27818

To remediate this vulnerability, upgrade all affected Terriajs server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

terriajs-server fixed: 4.0.3 
npm install terriajs-server@4.0.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls terriajs-server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27818, inspect your project dependencies using npm:

npm ls terriajs-server

Analyze the terminal output to locate any version of Terriajs server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.0.3), your application is affected.

Note: The npm ls terriajs-server command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In Terriajs server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact 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`: - ✅ example.com is allowed (correct) - ✅ api.example.com is allowed (correct) - ⚠️ maliciousexample.com is allowed (incorrect) An attacker could register maliciousexample.com and proxy content through `terriajs-server`, bypassing proxy restrictions. ### Patches All versions up to 4.0.2 are affected. Upgrade to 4.0.3 to address the vulnerability.

CVE-2026-27818 Affected Terriajs server Versions

1 component(s)
Fixed Versions:
4.0.3
Product / Package Ecosystem Affected Versions Fixed Version
terriajs-server
npm/terriajs-server
npm
< 4.0.3
4.0.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/TerriaJS/terriajs-server/security/advisories/GHSA-w789-49fc-v8hr
NVD — CVE-2026-27818 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27818
Security Fix Commit FIX COMMIT
https://github.com/TerriaJS/terriajs-server/commit/3aaa5d9717162b245ae4569232bbe7d8673c913f
Terriajs server Source Repository REPOSITORY
https://github.com/TerriaJS/terriajs-server
Terriajs server Release RELEASE
https://github.com/TerriaJS/terriajs-server/releases/tag/4.0.3

Frequently Asked Questions

What is CVE-2026-27818?
CVE-2026-27818 is a security vulnerability in Terriajs server involving TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist under CWE-20: Improper Input Validation.
Which Terriajs server versions are affected?
Affected versions include releases prior to 4.0.3 across affected packages: terriajs-server.
What version fixes CVE-2026-27818?
Upgrading to 4.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is terriajs-server affected?
Yes, terriajs-server is affected in releases prior to 4.0.3. Upgrade your dependency to 4.0.3 or later.
What CWE is associated with CVE-2026-27818?
CVE-2026-27818 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check npm dependencies for CVE-2026-27818?
Run the dependency tree command: 'npm ls terriajs-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-w789-49fc-v8hr",
  "modified" : "2026-02-26T15:22:11Z",
  "published" : "2026-02-26T15:22:11Z",
  "aliases" : [ "CVE-2026-27818" ],
  "summary" : "TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist",
  "details" : "### Impact\nA validation bug allows an attacker to proxy domains not explicitly allowed in the `proxyableDomains` configuration.\n\nThe validation only checks if a hostname _ended_ with an allowed domain. This meant:\n\nIf `example.com` is allowed in `proxyableDomains`:\n\n- ✅ example.com is allowed (correct)\n- ✅ api.example.com is allowed (correct)\n- ⚠️ maliciousexample.com is allowed (incorrect)\n\nAn attacker could register maliciousexample.com and proxy content through `terriajs-server`, bypassing proxy restrictions.\n\n### Patches\nAll versions up to 4.0.2 are affected. Upgrade to 4.0.3 to address the vulnerability.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "terriajs-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.0.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/TerriaJS/terriajs-server/security/advisories/GHSA-w789-49fc-v8hr"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27818"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TerriaJS/terriajs-server/commit/3aaa5d9717162b245ae4569232bbe7d8673c913f"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/TerriaJS/terriajs-server"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/TerriaJS/terriajs-server/releases/tag/4.0.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20", "CWE-918" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-26T15:22:11Z",
    "nvd_published_at" : "2026-02-26T00:16:26Z"
  }
}