CVE-2026-26861: CleverTap Web SDK is vulnerable to DOM-based XSS via handleCustomHtmlPreviewPostMessageEvent function
(updated )
CleverTap Web SDK version 1.15.2 and earlier is vulnerable to Cross-site Scripting (XSS) via window.postMessage. The handleCustomHtmlPreviewPostMessageEvent function in src/util/campaignRender/nativeDisplay.js performs insufficient origin validation using the includes() method, which can be bypassed by an attacker using a subdomain.
References
- github.com/CleverTap/clevertap-web-sdk
- github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js
- github.com/CleverTap/clevertap-web-sdk/commit/84695b726a751614ddc3a4f71382c239c5833e03
- github.com/CleverTap/clevertap-web-sdk/issues/424
- github.com/CleverTap/clevertap-web-sdk/pull/417
- github.com/advisories/GHSA-j5mf-6rh3-rhgg
- nvd.nist.gov/vuln/detail/CVE-2026-26861
Code Behaviors & Features
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