Vulnerabilities in pkg:npm/clevertap-web-sdk

PACKAGE
Advisory Identifier: GHSA-jfrq-hj9f-c8qx
Share
Advisory Summary

CVE-2026-26862 is a HIGH (CVSS 8.3) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Clevertap web sdk libraries in the npm ecosystem. The issue involves clevertap web sdk is vulnerable to dom-based cross-site scripting (xss) via window.postmessage. Remediation is available by upgrading affected packages to version 1.15.3.

2 Known Advisory Record(s)
Package Vulnerability Intelligence

pkg:npm/clevertap-web-sdk

2 Known Advisory Record(s)

Vulnerability advisories affecting package pkg:npm/clevertap-web-sdk. Select an advisory below to view technical details or fixes.

Advisory ID CVE / NVD Severity Summary
GHSA-jfrq-hj9f-c8qx CVE-2026-26862 HIGH CleverTap Web SDK is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage
GHSA-j5mf-6rh3-rhgg CVE-2026-26861 HIGH CleverTap Web SDK is vulnerable to DOM-based XSS via handleCustomHtmlPreviewPostMessageEvent function

CVE-2026-26862 at a Glance

CVE Identifier CVE-2026-26862
GHSA Identifier GHSA-jfrq-hj9f-c8qx
Severity HIGH
CVSS v3.1 Base Score 8.3
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Clevertap web sdk
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.3

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-26862

To remediate this vulnerability, upgrade all affected Clevertap web sdk dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

clevertap-web-sdk fixed: 1.15.3 
npm install clevertap-web-sdk@1.15.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls clevertap-web-sdk

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-26862, inspect your project dependencies using npm:

npm ls clevertap-web-sdk

Analyze the terminal output to locate any version of Clevertap web sdk in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.15.3), your application is affected.

Note: The npm ls clevertap-web-sdk command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Clevertap web sdk, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

CleverTap Web SDK version 1.15.2 and earlier is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage in the Visual Builder module. The origin validation in src/modules/visualBuilder/pageBuilder.js (lines 56-60) uses the includes() method to verify the originUrl contains "dashboard.clevertap.com", which can be bypassed by an attacker using a crafted subdomain.

CVE-2026-26862 Affected Clevertap web sdk Versions

1 component(s)
Fixed Versions:
1.15.3
Product / Package Ecosystem Affected Versions Fixed Version
clevertap-web-sdk
npm/clevertap-web-sdk
npm
< 1.15.3
1.15.3

References

NVD — CVE-2026-26862 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-26862
Clevertap web sdk Source Repository REPOSITORY
https://github.com/CleverTap/clevertap-web-sdk/issues/442
Clevertap web sdk Source Repository REPOSITORY
https://github.com/CleverTap/clevertap-web-sdk/pull/417
Security Fix Commit FIX COMMIT
https://github.com/CleverTap/clevertap-web-sdk/commit/766f75f0c9082a27eb0b59c9fa4b0d9b19ba3d10
Security Fix Commit FIX COMMIT
https://github.com/CleverTap/clevertap-web-sdk/commit/84695b726a751614ddc3a4f71382c239c5833e03
Clevertap web sdk Source Repository REPOSITORY
https://github.com/CleverTap/clevertap-web-sdk
Clevertap web sdk Source Repository REPOSITORY
https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/modules/visualBuilder/pageBuilder.js#L56-L60

Frequently Asked Questions

What is CVE-2026-26862?
CVE-2026-26862 is a security vulnerability in Clevertap web sdk involving CleverTap Web SDK is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Clevertap web sdk versions are affected?
Affected versions include releases prior to 1.15.3 across affected packages: clevertap-web-sdk.
What version fixes CVE-2026-26862?
Upgrading to 1.15.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is clevertap-web-sdk affected?
Yes, clevertap-web-sdk is affected in releases prior to 1.15.3. Upgrade your dependency to 1.15.3 or later.
What is the CVSS score of CVE-2026-26862?
CVE-2026-26862 has a CVSS v3.1 base score of 8.3 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L.
What CWE is associated with CVE-2026-26862?
CVE-2026-26862 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2026-26862?
Run the dependency tree command: 'npm ls clevertap-web-sdk'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-jfrq-hj9f-c8qx",
  "modified" : "2026-03-01T01:26:39Z",
  "published" : "2026-02-27T18:31:06Z",
  "aliases" : [ "CVE-2026-26862" ],
  "summary" : "CleverTap Web SDK is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage",
  "details" : "CleverTap Web SDK version 1.15.2 and earlier is vulnerable to DOM-based Cross-Site Scripting (XSS) via window.postMessage in the Visual Builder module. The origin validation in src/modules/visualBuilder/pageBuilder.js (lines 56-60) uses the includes() method to verify the originUrl contains \"dashboard.clevertap.com\", which can be bypassed by an attacker using a crafted subdomain.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "clevertap-web-sdk"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.15.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-26862"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/CleverTap/clevertap-web-sdk/issues/442"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/CleverTap/clevertap-web-sdk/pull/417"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/CleverTap/clevertap-web-sdk/commit/766f75f0c9082a27eb0b59c9fa4b0d9b19ba3d10"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/CleverTap/clevertap-web-sdk/commit/84695b726a751614ddc3a4f71382c239c5833e03"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/CleverTap/clevertap-web-sdk"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/modules/visualBuilder/pageBuilder.js#L56-L60"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-01T01:26:39Z",
    "nvd_published_at" : "2026-02-27T18:16:12Z"
  }
}