CVE-2026-26862

CleverTap Web SDK is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage

8.3 HighFix available

CleverTap Web SDK version 1.15.2 and earlier is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage in the Visual Builder module. The origin validation in src/modules/visualBuilder/pageBuilder.js (lines 56-60) uses the includes() method to verify the originUrl contains "dashboard.clevertap.com", which can be bypassed by an attacker using a crafted subdomain

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Required

What an attacker can affect

Confidentiality: High
Integrity: High
Availability: Low

Exploit likelihood

0.42%Up 0.4 points since Feb 28, 2026

What each source reports

CVE List Score used 8.3

Record: CVE-2026-26862
CVSS 3.1: 8.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Weakness: CWE-829, CWE-79
Updated: 2026-11-02

EUVDEUVD-2026-9039 8.3

Record: EUVD-2026-9039
CVSS 3.1: 8.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Updated: 2026-11-02

GitHub AdvisoriesGHSA-jfrq-hj9f-c8qx 8.3

CleverTap Web SDK is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage

Record: GHSA-jfrq-hj9f-c8qx
CVSS 3.1: 8.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Weakness: CWE-79
Updated: 2026-11-02

NVD 8.3

Record: CVE-2026-26862
CVSS 3.1: 8.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Weakness: CWE-79, CWE-829
Updated: 2026-11-02

OSV 8.3

Record: CVE-2026-26862
CVSS 3.1: 8.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Updated: 2026-11-02

OSVGHSA-jfrq-hj9f-c8qx 8.3

CleverTap Web SDK is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage

Record: GHSA-jfrq-hj9f-c8qx
CVSS 3.1: 8.3 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Weakness: CWE-79
Updated: 2026-11-02

Affected products

clevertap web sdk

Affected packages

Affected packages
Package	Affected	Fixed
`clevertap-web-sdk` npm	before 1.15.3	1.15.3

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-26862 is a high vulnerability (CVSS 8.3) in Clevertap Web Sdk, published February 27, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.42%, the 36th percentile. Fixed in clevertap-web-sdk 1.15.3.