high8.3
CVE-2026-26861
CleverTap Web SDK is vulnerable to DOM-based XSS via handleCustomHtmlPreviewPostMessageEvent function
Impact
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
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | clevertap-web-sdk | < 1.15.3 | 1.15.3 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Clevertap | Clevertap Web Sdk | through 1.15.2 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121
- https://github.com/CleverTap/clevertap-web-sdk/issues/424
- https://github.com/CleverTap/clevertap-web-sdk/pull/417
- https://github.com/advisories/GHSA-j5mf-6rh3-rhgg
- https://nvd.nist.gov/vuln/detail/CVE-2026-26861
- https://github.com/CleverTap/clevertap-web-sdk/commit/84695b726a751614ddc3a4f71382c239c5833e03