What’s Vulnerable › Vulnerabilities

CVE-2026-26861

• Severity: high (CVSS 8.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-02-27 · updated 2026-06-17
• Weakness: CWE-346

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 products

• Clevertap Web Sdk: through 1.15.2

References

• 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

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