Which versions of CesiumGS CesiumJS are affected by CVE-2026-3990?

Organizations using CesiumGS CesiumJS should be aware of moderate risk from CVE-2026-3990, a cross-site scripting vulnerability rated CVSS 4.3.

How to fix or mitigate CVE-2026-3990?

Within 30 days: Identify affected systems running CesiumGS CesiumJS and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

CesiumGS CesiumJS CVE-2026-3990

Q: What is the CVSS score of CVE-2026-3990?

CVE-2026-3990 has a CVSS 4.0 base score of 2.1 (Low). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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. EPSS exploitation probability: 0.0%.

LOW

Cross-site Scripting (XSS) (CWE-79)

2026-03-12 cna@vuldb.com

XSS

2.1

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

2.1 LOW

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

Severity Changed

Apr 29, 2026 - 01:11 NVD

MEDIUM LOW

CVSS changed

Apr 29, 2026 - 01:11 NVD

5.3 (MEDIUM) 2.1 (LOW)

CVSS changed

Apr 22, 2026 - 21:37 NVD

4.3 (MEDIUM) 5.3 (MEDIUM)

Analysis Generated

Mar 12, 2026 - 19:57 vuln.today

CVE Published

Mar 12, 2026 - 06:16 nvd

MEDIUM 4.3

DescriptionCVE.org

A security flaw has been discovered in CesiumGS CesiumJS up to 1.137.0. Affected by this issue is some unknown functionality of the file Apps/Sandcastle/standalone.html. The manipulation of the argument c results in cross site scripting. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks. The presence of this vulnerability remains uncertain at this time. The vendor was contacted early about this disclosure but did not respond in any way. According to CVE-2023-48094, "the vendor's position is that Apps/Sandcastle/standalone.html is part of the CesiumGS/cesium GitHub repository, but is demo code that is not part of the CesiumJS JavaScript library product."

AnalysisAI

Stored cross-site scripting in CesiumJS up to version 1.137.0 allows unauthenticated remote attackers to inject malicious scripts through the parameter 'c' in Apps/Sandcastle/standalone.html, with public exploit code already available. While the vendor classifies this as demo code outside the core library product, the vulnerability affects users running vulnerable versions of the application. No patch is currently available.

Technical ContextAI

This vulnerability (CWE-79: Cross-site Scripting (XSS)) affects A security flaw has been discovered in CesiumGS CesiumJS. A security flaw has been discovered in CesiumGS CesiumJS up to 1.137.0. Affected by this issue is some unknown functionality of the file Apps/Sandcastle/standalone.html. The manipulation of the argument c results in cross site scripting. The attack can be launched remotely. The exploit has been released to the public and may be used for attacks. The presence of this vulnerability remains uncertain at this time. The vendor was contacted early about this disclosure but did not respond in any way.

Affected ProductsAI

Product: A security flaw has been discovered in CesiumGS CesiumJS. Versions: up to 1.137.0..

RemediationAI

Monitor vendor advisories for a patch. Implement output encoding and Content Security Policy headers. Restrict network access to the affected service where possible.