CVE-2026-26861

Name: CVE-2026-26861
Creator: NVD / NIST
Published: 2026-02-27T18:16:12.043+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.3/10EPSS 0.18%

Last modified Jun 17, 2026

CVE-2026-26861 is a high-severity vulnerability rated 8.3/10 on the CVSS scale. 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. EPSS estimates a 0.18% chance of exploitation in the next 30 days.

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

Metrics

CVSS 3.1

8.3/10

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

EPSS Probability

0.18%

7.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-346

Affected Software

Vendor	Product	Versions
Clevertap	Clevertap Web Sdk	<= 1.15.2

References

https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121Product
https://github.com/CleverTap/clevertap-web-sdk/issues/424Exploit, Issue Tracking, Vendor Advisory
https://github.com/CleverTap/clevertap-web-sdk/pull/417Patch

Timeline

Published: Feb 27, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-26861?

How severe is CVE-2026-26861?

CVE-2026-26861 has a CVSS score of 8.3/10 (HIGH severity). The EPSS model estimates a 0.18% probability of exploitation in the next 30 days.

How do I fix CVE-2026-26861?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-26861?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST