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TI-2026-21399 Aliases CVE-2026-26861GHSA-j5mf-6rh3-rhgg

CleverTap Web SDK version 1.15.2 and earlier is vulnerable to Cross-Site Scripting (XSS)…

Priority HIGH 69CWE-346Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Security bypass, Cross-site scripting
Confidentiality · integrity · availability
High · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and GitHub. Impact type from CWE-346 and CWE-79.

Summary

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

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00205 10th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed clevertap-web-sdk (npm): 1.15.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
——all versions—No fix listedCNA
—clevertap-web-sdk (npm)before 1.15.31.15.3Patch availableGHSA-j5mf-6rh3-rhgg
  • — Vendor— Affected all versions Fixed in — No fix listed CNA
  • clevertap-web-sdk (npm) Vendor— Affected before 1.15.3 Fixed in 1.15.3 Patch available GHSA-j5mf-6rh3-rhgg

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:clevertap:clevertap_web_sdk:*:*:*:*:*:*:*:*up to 1.15.2VulnerableCleverTap
  • cpe:2.3:a:clevertap:clevertap_web_sdk:*:*:*:*:*:*:*:* Versions up to 1.15.2 Vulnerable ·CleverTap

Remediation

  • Fix · GHSA-j5mf-6rh3-rhgg clevertap-web-sdk (npm) Fixed in 1.15.3 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-26861
  2. 2026-10-03 Alias added: GHSA-j5mf-6rh3-rhgg

References

Exploit 1

Patch 1

Advisory 1

Other 3

  • TI-2026-21400 CleverTap Web SDK version 1.15.2 and earlier is vulnerable to DOM-based Cross-Site… CVSS 3.1HIGH 8.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences