Clevertap · Clevertap Web Sdk · CVE-2026-26861
**Name of the Vulnerable Software and Affected Versions**
CleverTap Web SDK versions 1.15.2 and earlier
**Description**
The CleverTap Web SDK is susceptible to a Cross-Site Scripting (XSS) issue through the `window.postMessage` functionality. The `handleCustomHtmlPreviewPostMessageEvent` function, located in `src/util/campaignRender/nativeDisplay.js`, does not adequately validate the message origin using the `includes()` method, allowing attackers to bypass security checks by utilizing a subdomain.
**Recommendations**
Update CleverTap Web SDK to a version later than 1.15.2.