What is the CVSS score of CVE-2026-26861?

CVE-2026-26861 has a CVSS 3.1 base score of 8.3 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L. EPSS exploitation probability: 0.0%.

Which versions of Clevertap Web Sdk are affected by CVE-2026-26861?

CleverTap Web SDK versions 1.15.2 and earlier contain a cross-site scripting vulnerability that could allow attackers to execute malicious code in user browsers, potentially compromising customer…. A patch is available.

Is there a public PoC exploit available for CVE-2026-26861?

Yes, a public proof-of-concept exploit is available for CVE-2026-26861. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-26861?

Within 24 hours: Inventory all applications and systems using CleverTap Web SDK and identify current versions in production. Within 7 days: Apply the available vendor patch to all affected instances and validate in staging environments. Within 30 days: Complete production deployment across all affected systems and verify patch installation through vulnerability scanning.

Clevertap Web Sdk CVE-2026-26861

HIGH

Origin Validation Error (CWE-346)

2026-02-27 cve@mitre.org

GHSA-j5mf-6rh3-rhgg

XSS Clevertap Web Sdk

8.3

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

8.3 HIGH

AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

Low

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

PoC Detected

Mar 03, 2026 - 18:46 vuln.today

Public exploit code

Patch released

Mar 03, 2026 - 18:46 nvd

Patch available

CVE Published

Feb 27, 2026 - 18:16 nvd

HIGH 8.3

DescriptionCVE.org

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

AnalysisAI

CleverTap Web SDK through version 1.15.2 contains a cross-site scripting vulnerability in its postMessage handler that fails to properly validate message origins, allowing attackers to inject malicious scripts by exploiting subdomain bypass techniques. Public exploit code exists for this vulnerability, and affected applications can be compromised through user interaction. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access

Attacker crafts malicious postMessage from subdomain

Exploit

handleCustomHtmlPreviewPostMessageEvent bypasses origin validation

Execution

Inject arbitrary JavaScript into victim's browser context

Impact

Execute XSS payload with user privileges