Security readout for executives and security teams
Plain-English summary
CleverTap Web SDK 1.15.2 and earlier has an XSS weakness in postMessage handling. A malicious site could potentially bypass origin checks using a crafted subdomain and run script in a user’s browser if the user interaction condition is met. Sites embedding affected SDK versions should prioritize inventory and vendor-guided remediation.
Executive priority
Treat as a high-priority web application dependency issue. It affects browser trust boundaries and could expose users to script execution. Immediate action should focus on finding affected deployments, following CleverTap guidance, and updating or reducing exposure where business-critical user flows are involved.
Technical view
The issue is CWE-346: insufficient origin validation. handleCustomHtmlPreviewPostMessageEvent in src/util/campaignRender/nativeDisplay.js reportedly uses includes() for origin checks, allowing bypass by attacker-controlled subdomains. CVSS is 8.3 high, network reachable, low complexity, no privileges required, user interaction required, with high confidentiality and integrity impact.
Likely exposure
Exposure is likely for web applications that include CleverTap Web SDK version 1.15.2 or earlier, especially where the vulnerable native display/custom HTML preview code is present. The source bundle does not identify CPEs or a fixed release version.
Exploitation context
The CVE record indicates exploitation requires user interaction and network access. The provided sources and KEV status do not show known active exploitation. The impact is browser-side XSS, which can affect user sessions, page data, or site trust depending on implementation.
Researcher notes
Evidence is limited to the CVE record and linked GitHub issue, pull request, and vulnerable code location. No public exploit or active exploitation signal is provided in the bundle. Avoid assuming a fixed version unless confirmed by CleverTap release notes or repository guidance.
Mitigation direction
- Inventory all applications using CleverTap Web SDK.
- Prioritize sites running version 1.15.2 or earlier.
- Review CleverTap issue 424 and PR 417 for correction status.
- Apply vendor-recommended updates or code changes when available.
- Consider reducing exposure of affected functionality until remediated.
Validation and detection
- Check package manifests and lockfiles for CleverTap Web SDK versions.
- Inspect deployed bundles for CleverTap Web SDK 1.15.2 or earlier.
- Review nativeDisplay.js for includes()-based origin validation.
- Confirm whether deployed code includes the PR 417 changes.
- Document affected pages and business owners for remediation tracking.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-346: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-26861 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L2.85.5Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.3HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L
Source materials
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Origin Validation Error
Origin Validation Error represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.