A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via...
Summary
Cross-site scripting reported (CVE-2026-6658). Risk of unauthorized operations or information disclosure. Exploitable via data_mermaid.
Original description
The description as published by the source.
A vulnerability in jupyter/nbconvert versions <= 7.17.0 allows for Cross-site Scripting (XSS) via unsanitized text/vnd.mermaid output in HTML exports. The data_mermaid block in share/templates/lab/base.html.j2 renders text/vnd.mermaid cell output directly into HTML without escaping, enabling attackers to inject arbitrary HTML/JavaScript by breaking out of the `` tag. This vulnerability impacts any server using nbconvert to render notebooks as HTML, allowing attackers to execute arbitrary JavaScript in the context of users viewing the HTML export.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-6658 has been found.
Attackers can target a specific entry point like data_mermaid over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2026-6658" on the vendor's site.
CVE-2026-6658 — CWE-79 / CVSS v3 5.4
Attack vector: remote (network-reachable)
Attack surface: data_mermaid
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) has been reported. Attackers reach the vulnerable code path via data_mermaid.
Check the vendor advisory for the affected versions. Attack surface: data_mermaid.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
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2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-6658 nbconvert
- Ubuntu UBUNTU-CVE-2026-6658 nbconvert
References
- web nvd.nist.gov
- web huntr.com
- web github.com