Cross-Site Scripting (XSS) in astro (CVE-2026-50146)
Summary
Cross-site scripting in astro (CVE-2026-50146). Data can be tampered with by attackers. Exploitable via astro.config.mjs. Mitigation: upgrade to 6.3.3 or later.
Original description
The description as published by the source.
Astro is a web framework. Prior to 6.3.3, when a component uses a client:* directive, Astro inserts named slot content into a data-astro-template attribute without HTML escaping the slot name allowing an attacker to break out of the attribute context and inject arbitrary HTML, resulting in reflected XSS during SSR. This vulnerability is fixed in 6.3.3.
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-2026-50146 has been found in astro.
Attackers can target a specific entry point like astro.config.mjs over the network to misuse the product.
Data can be tampered with by attackers. CVSS score: 7.1/10.
What to do: upgrade astro to 6.3.3 or later.
If unsure, ask your IT team or search "astro CVE-2026-50146" on the vendor's site.
CVE-2026-50146 (astro) — CWE-79 / CVSS v3 7.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: astro.config.mjs
Patched: 6.3.3 — apply immediately
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) exists in astro. Attackers reach the vulnerable code path via astro.config.mjs without authentication.
Check the vendor advisory for the affected versions of astro. Attack surface: astro.config.mjs.
Severity: High (CVSS 7.1/10). Data can be tampered with by attackers.
Update to 6.3.3.
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. Run grep -r 'astro' . against your dependency files (package-lock.json, requirements.txt, go.sum) 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
grep -r 'astro' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
astroを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade astro to 6.3.3ステージング環境で 6.3.3 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
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3Post-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。
Affected packages
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com