What is CVE-2026-26861?

CVE-2026-26861 is a high-severity vulnerability in Clevertap Web Sdk, classified under Origin Validation Error. CVSS score: 8.3/10. Published 2026-02-27.

How severe is CVE-2026-26861?

High severity. CVSS v3 base score is 8.3 out of 10.

Vulnerability in Clevertap Web Sdk

CVE-2026-26861

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: 0.002 (8.0th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L.

Affected products

Clevertap Clevertap_web_sdk
N/a — versions n/a

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

cve@mitre.org (Exploit, Issue Tracking, Vendor Advisory)
cve@mitre.org (Patch)
cve@mitre.org (Product)

Frequently asked questions

What is CVE-2026-26861?: CVE-2026-26861 is a high-severity vulnerability in Clevertap Web Sdk, classified under Origin Validation Error. CVSS score: 8.3/10. Published 2026-02-27.
How severe is CVE-2026-26861?: High severity. CVSS v3 base score is 8.3 out of 10.