{"id":"GHSA-j5mf-6rh3-rhgg","summary":"CleverTap Web SDK  is vulnerable to DOM-based XSS via handleCustomHtmlPreviewPostMessageEvent function","details":"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.","aliases":["CVE-2026-26861"],"modified":"2026-03-04T15:12:09.217040Z","published":"2026-02-27T18:31:06Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-03-01T01:26:26Z","nvd_published_at":"2026-02-27T18:16:12Z","cwe_ids":["CWE-346","CWE-79"],"severity":"HIGH"},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26861"},{"type":"WEB","url":"https://github.com/CleverTap/clevertap-web-sdk/issues/424"},{"type":"WEB","url":"https://github.com/CleverTap/clevertap-web-sdk/pull/417"},{"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/util/campaignRender/nativeDisplay.js#L118-L121"}],"affected":[{"package":{"name":"clevertap-web-sdk","ecosystem":"npm","purl":"pkg:npm/clevertap-web-sdk"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.15.3"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-j5mf-6rh3-rhgg/GHSA-j5mf-6rh3-rhgg.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L"}]}