CVE-2026-26861 — HIGH (8.3)

Q: How severe is CVE-2026-26861?

CVE-2026-26861 has been rated HIGH with a CVSS base score of 8.3/10. Review the CVSS metrics above for detailed severity breakdown.

Q: Is there a patch for CVE-2026-26861?

Check the references section above for vendor advisories and patch information. Affected products include: Clevertap Clevertap Web Sdk.

Vulnerability 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

CVSS Score

8.3

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

LOW

Affected Products

Vendor	Product	Versions
Clevertap	Clevertap Web Sdk	<= 1.15.2

Related Weaknesses (CWE)

CWE-346

References

https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRenProduct
https://github.com/CleverTap/clevertap-web-sdk/issues/424ExploitIssue TrackingVendor Advisory
https://github.com/CleverTap/clevertap-web-sdk/pull/417Patch

FAQ

What is CVE-2026-26861?

CVE-2026-26861 is a vulnerability with a CVSS score of 8.3 (HIGH). 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/nativeD...

How severe is CVE-2026-26861?

CVE-2026-26861 has been rated HIGH with a CVSS base score of 8.3/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-26861?

Check the references section above for vendor advisories and patch information. Affected products include: Clevertap Clevertap Web Sdk.