HOMEVULNERABILITIESCVE-2026-26861
HIGH

CVE-2026-26861

Published: February 27, 2026· Updated: Mar 3, 2026

8.3
CVSS v3.1
EPSS:0.02%probability of exploitation in 30 daysPercentile:3.6th

Official 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

NVD Source

Technical Analysis

CVE-2026-26861 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 8.3.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityLow
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

Affected Vendors & Products

clevertap1 product
clevertap web sdk
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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Official Patches & Advisories

PATCHhttps://github.com/CleverTap/clevertap-web-sdk/pull/417
ADVISORYhttps://github.com/CleverTap/clevertap-web-sdk/issues/424

All References (3)

→
https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121Product
→
https://github.com/CleverTap/clevertap-web-sdk/issues/424Exploit · Issue Tracking · Vendor Advisory
→
https://github.com/CleverTap/clevertap-web-sdk/pull/417Patch

Quick Facts

CVE IDCVE-2026-26861
CVSS Score8.3 / 10
SeverityHIGH
CISA KEVNo
EPSS (30d)0.02%
Affected1 vendor
PublishedFeb 27, 2026

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-26861 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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