DOM XSS via substring-based postMessage origin validation
Published Feb 27, 2026 · Updated Feb 27, 2026
DOM-based XSS in CleverTap Web SDK 1.15.2 and earlier allows remote attackers to execute JavaScript through a crafted postMessage. Visual Builder's pageBuilder.js accepts an event origin when includes() finds dashboard.clevertap.com anywhere in it, then writes unsanitized selector HTML to element.outerHTML. Exploitation requires a site using the vulnerable SDK and user interaction with an attacker-controlled origin; successful code runs in the site's browser context.
Summary
What happened
DOM-based XSS in CleverTap Web SDK 1.15.2 and earlier allows remote attackers to execute JavaScript through a crafted postMessage. Visual Builder's pageBuilder.js accepts an event origin when includes() finds dashboard.clevertap.com anywhere in it, then writes unsanitized selector HTML to element.outerHTML. Exploitation requires a site using the vulnerable SDK and user interaction with an attacker-controlled origin; successful code runs in the site's browser context.
The record
- CVE
- CVE-2026-26862
- Published
- Feb 27, 2026
- Updated
- Feb 27, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-829, CWE-79, T1059.007
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 27, 2026CVE publishedPublication date reported by the CVE source.
- Feb 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GitHub issue #442 postMessage DOM-XSS payloadproof of concept · unverified
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Technologies
Your stack
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Your stack
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