CVE-2026-26861

HIGHPre-NVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cisa-adp, epss
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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

CVSS v3
8.3
EG Score
8.3(medium)
EG Risk
42(Track)
EG Risk 42/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity83% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
8%
KEV
Not listed

Published

February 27, 2026

Last Modified

June 17, 2026

Advisory Details (3)

Auto-updated Aug 2, 2026
🔬 Proof of concept available. Patch available. Sources: github_pr.
github_pr Patch Available

Added origin check in postMessage

Patch available: CleverTap/clevertap-web-sdk v2.0.1 (PR #417 merged 2025-05-22)

https://github.com/CleverTap/clevertap-web-sdk/pull/417
generic🟡 PoC Available

DOM-XSS via postMessage in CleverTap Web SDK in 1.15.2 version · Issue #424 · CleverTap/clevertap-web-sdk · GitHub

https://github.com/CleverTap/clevertap-web-sdk/issues/424
generic

clevertap-web-sdk/src/util/campaignRender/nativeDisplay.js at cf1b65d70e02247fffcaee76e1bc4f82ce429c0d · CleverTap/clevertap-web-sdk · GitHub

https://github.com/CleverTap/clevertap-web-sdk/blob/cf1b65d/src/util/campaignRender/nativeDisplay.js#L118-L121

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
clevertap-web-sdk—1.15.3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 28× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 13:03 UTCOSV refresh
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 19:27 UTCEPSS rescore
  4. 2026-09-17 19:30 UTCEPSS rescore
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-13 16:47 UTCEPSS rescore
  8. 2026-09-12 15:01 UTCEPSS rescore
  9. 2026-09-11 14:52 UTCEPSS rescore
  10. 2026-09-10 09:34 UTCEPSS rescore
  11. 2026-09-08 22:00 UTCEPSS rescore
  12. 2026-09-07 16:01 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-06 13:47 UTCEPSS rescore
  15. 2026-09-04 05:06 UTCEPSS rescore
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-08-31 17:04 UTCOSV refresh
  20. 2026-08-30 19:17 UTCEPSS rescore
  21. 2026-08-30 01:22 UTCEPSS rescore
  22. 2026-08-28 21:41 UTCEPSS rescore
  23. 2026-08-27 14:25 UTCEPSS rescore
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-25 13:48 UTCEPSS rescore
Show 36 more
  1. 2026-08-23 00:19 UTCEPSS rescore
  2. 2026-08-21 23:49 UTCEPSS rescore
  3. 2026-08-20 22:55 UTCEPSS rescore
  4. 2026-08-19 17:03 UTCEPSS rescore
  5. 2026-08-18 13:48 UTCEPSS rescore
  6. 2026-08-17 13:47 UTCEPSS rescore
  7. 2026-08-16 14:56 UTCEPSS rescore
  8. 2026-08-16 02:14 UTCEPSS rescore
  9. 2026-08-15 01:30 UTCEPSS rescore
  10. 2026-08-14 08:49 UTCEG score recompute
  11. 2026-08-13 22:00 UTCEPSS rescore
  12. 2026-08-13 00:45 UTCEG score recompute
  13. 2026-08-12 13:50 UTCEPSS rescore
  14. 2026-08-11 23:33 UTCEG score recompute
  15. 2026-08-11 13:42 UTCEPSS rescore
  16. 2026-08-11 06:08 UTCEG score recompute
  17. 2026-08-11 00:00 UTCEPSS rescore
  18. 2026-08-09 21:00 UTCEG score recompute
  19. 2026-08-09 13:46 UTCEPSS rescore
  20. 2026-08-09 08:27 UTCEG score recompute
  21. 2026-08-08 16:37 UTCEPSS rescore
  22. 2026-08-07 20:26 UTCEG score recompute
  23. 2026-08-06 13:46 UTCEPSS rescore
  24. 2026-08-06 02:54 UTCEG score recompute
  25. 2026-08-05 19:17 UTCEPSS rescore
  26. 2026-08-04 15:10 UTCEPSS rescore
  27. 2026-08-04 04:52 UTCEG score recompute
  28. 2026-08-03 10:36 UTCEPSS rescore
  29. 2026-08-02 19:21 UTCEG score recompute
  30. 2026-08-02 02:26 UTCEPSS rescore
  31. 2026-08-01 04:16 UTCEPSS rescore
  32. 2026-07-30 16:27 UTCEPSS rescore
  33. 2026-07-30 01:30 UTCEPSS rescore
  34. 2026-07-28 15:36 UTCEPSS rescore
  35. 2026-07-27 14:03 UTCEG score recompute
  36. 2026-07-27 13:55 UTCOSV refresh

Frequently asked(5)

What is CVE-2026-26861?
CVE-2026-26861 is a high vulnerability published on February 27, 2026. 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…
When was CVE-2026-26861 disclosed?
CVE-2026-26861 was first published in the National Vulnerability Database on February 27, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-26861 actively exploited?
CVE-2026-26861 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 92.0% of all scored CVEs.
What is the CVSS score of CVE-2026-26861?
CVE-2026-26861 has a CVSS v3.1 base score of 8.3 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-26861?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-26861, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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