# CVE-2026-126814: blueprintUE Self-Hosted Edition before 4.3.6 Arbitrary Iframe Embedding via PeerTube Matcher

Status: published. Published: 2026-11-11. Updated: 2026-11-13.

blueprintUE Self-Hosted Edition before 4.3.6 contains an iframe injection vulnerability that allows authenticated users to embed arbitrary third-party content by abusing the PeerTube video URL matcher in BlueprintService::findVideoProvider(). Attackers can set a blueprint video URL on an attacker-controlled host, which site.js loads in an unsandboxed iframe after consent, framing fake login forms or malware downloads.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/blueprintue/blueprintue-self-hosted-edition/commit/5f13e2bb8cd4c620899e9f8afd41a6e62b3bc6a4
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/blueprintue/blueprintue-self-hosted-edition/pull/269

## Affected products and versions

- blueprintue / blueprintue-self-hosted-edition (blueprintue/blueprintue-self-hosted-edition): ≥ 1.0.0; < 4.3.6 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 4.8 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 3.5 (low); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 4.8 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 3.5 (low); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.26% as of 2026-11-13; percentile 17.49%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-829

## Exploit evidence

- exploit: https://github.com/blueprintue/blueprintue-self-hosted-edition/security/advisories/GHSA-3vgc-fcfg-v233 (ADP: CISA-ADP)

## References

- https://github.com/blueprintue/blueprintue-self-hosted-edition/security/advisories/GHSA-3vgc-fcfg-v233 (CNA: VulnCheck; vendor-advisory)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/commit/5f13e2bb8cd4c620899e9f8afd41a6e62b3bc6a4 (CNA: VulnCheck; patch)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/pull/269 (CNA: VulnCheck; issue-tracking, patch)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/releases/tag/v4.3.6 (CNA: VulnCheck; release-notes)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/blob/v4.3.5/app/services/www/BlueprintService.php#L700-L716 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/blueprintue-self-hosted-edition-before-4.3.6-arbitrary-iframe-embedding-via-peertube-matcher (CNA: VulnCheck; third-party-advisory)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/security/advisories/GHSA-3vgc-fcfg-v233 (ADP: CISA-ADP; exploit)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/blob/v4.3.5/app/services/www/BlueprintService.php#L700-L716 (disclosure@vulncheck.com)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/commit/5f13e2bb8cd4c620899e9f8afd41a6e62b3bc6a4 (disclosure@vulncheck.com)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/pull/269 (disclosure@vulncheck.com)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/releases/tag/v4.3.6 (disclosure@vulncheck.com)

- https://github.com/blueprintue/blueprintue-self-hosted-edition/security/advisories/GHSA-3vgc-fcfg-v233 (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/blueprintue-self-hosted-edition-before-4.3.6-arbitrary-iframe-embedding-via-peertube-matcher (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-126814; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-126814; retrieved 2026-11-13; source updated 2026-11-12

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-126814; retrieved 2026-11-13; source updated Not reported

Revision: d0fa49f74edda195ee7c7d2de0410030c5a0e81048e38aab99a2d22dcf5cebba

Canonical: https://y2.dev/cve/CVE-2026-126814

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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