CVE-2026-26861
HIGH8.3EPSS 0.01%CleverTap Web SDK is vulnerable to DOM-based XSS via handleCustomHtmlPreviewPostMessageEvent function
Published: 2/27/2026Modified: 3/4/2026
Also known as:GHSA-j5mf-6rh3-rhgg
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.
Affected packages (1)
- npm/clevertap-web-sdkfrom 0, < 1.15.3
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L |
References (6)
- ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-26861
- PATCHhttps://github.com/CleverTap/clevertap-web-sdk
- WEBhttps://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121
- WEBhttps://github.com/CleverTap/clevertap-web-sdk/commit/84695b726a751614ddc3a4f71382c239c5833e03
- WEBhttps://github.com/CleverTap/clevertap-web-sdk/issues/424
- WEBhttps://github.com/CleverTap/clevertap-web-sdk/pull/417