CVE-2026-27818
TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist
TerriaJS-Server is a NodeJS Express server for TerriaJS, a library for building web-based geospatial data explorers. A validation bug in versions prior to 4.0.3 allows an attacker to proxy domains not explicitly allowed in the proxyableDomains configuration. Version 4.0.3 fixes the issue.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist
TerriaJS-Server is a NodeJS Express server for TerriaJS, a library for building web-based geospatial data explorers. A validation bug in versions prior to 4.0.3 allows an attacker to proxy domains not explicitly allowed in the proxyableDomains configuration. Version 4.0.3 fixes the issue.
- Record
CVE-2026-27818- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-20, CWE-918
- Updated
- 2026-11-02
EUVDEUVD-2026-8783
TerriaJS-Server is a NodeJS Express server for TerriaJS, a library for building web-based geospatial data explorers. A validation bug in versions prior to 4.0.3 allows an attacker to proxy domains not explicitly allowed in the proxyableDomains configuration. Version 4.0.3 fixes the issue.
- Record
EUVD-2026-8783- CVSS 4.0
- 8.7 High
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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w789-49fc-v8hr
TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist
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.
- Record
GHSA-w789-49fc-v8hr- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-20, CWE-918
- Updated
- 2026-11-02
NVD
TerriaJS-Server is a NodeJS Express server for TerriaJS, a library for building web-based geospatial data explorers. A validation bug in versions prior to 4.0.3 allows an attacker to proxy domains not explicitly allowed in the proxyableDomains configuration. Version 4.0.3 fixes the issue.
- Record
CVE-2026-27818- CVSS 4.0
- 8.7 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Weakness
- CWE-20, CWE-918
- Updated
- 2026-11-02
OSV
TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist
TerriaJS-Server is a NodeJS Express server for TerriaJS, a library for building web-based geospatial data explorers. A validation bug in versions prior to 4.0.3 allows an attacker to proxy domains not explicitly allowed in the proxyableDomains configuration. Version 4.0.3 fixes the issue.
- Record
CVE-2026-27818- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-20, CWE-918
- Updated
- 2026-11-02
OSVGHSA-w789-49fc-v8hr
TerriaJS-Server has a domain validation bypass vulnerability in its proxy allowlist
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.
- Record
GHSA-w789-49fc-v8hr- CVSS 4.0
- 8.7 High
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 - Weakness
- CWE-20, CWE-918
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
terriajs-servernpm |
before 4.0.3 | 4.0.3 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-27818 is a high vulnerability (CVSS 8.7) in Terria Terriajs-server, published February 26, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.28%, the 20th percentile. Fixed in terriajs-server 4.0.3.
References
github.com/TerriaJS/terriajs-server/security/advisories/GHSA-w789-49fc-v8hr
nvd.nist.gov/vuln/detail/CVE-2026-27818