GitHub Advisoryadvisory · npm
GHSA-j5mf-6rh3-rhgg CleverTap Web SDK is vulnerable to DOM-based XSS via handleCustomHtmlPreviewPostMessageEvent function
HIGH
Official page ↗
- Aliases
- CVE-2026-26861
- Ecosystem
- npm
- Packages
- clevertap-web-sdk
- Severity
- High
- CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
- Weaknesses
- CWE-346, CWE-79
- Reviewed
- 2026-03-01
Affected packages
• npm clevertap-web-sdk: < 1.15.3 → fixed in 1.15.3
Description
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.
Related
Alias · CVE (1)
- CVE-2026-26861 CleverTap Web SDK version 1.15.2 and earlier is vulnerable to Cross-Site Scripting (XSS) via window.postMessage. vulnerability
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-26861 advisory
- https://github.com/CleverTap/clevertap-web-sdk/issues/424 web
- https://github.com/CleverTap/clevertap-web-sdk/pull/417 web
- https://github.com/CleverTap/clevertap-web-sdk/commit/84695b726a751614ddc3a4f71382c239c5833e03 web
- https://github.com/CleverTap/clevertap-web-sdk package
- https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121 web