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TI-2026-36915 Aliases CVE-2026-50146GHSA-8hv8-536x-4wqp

Astro: Reflected XSS via unescaped slot name

Priority MEDIUM 64CWE-80Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Cross-site scripting
Confidentiality · integrity · availability
Low · High · None
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-80.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00268 19th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Fixed astro (withastro): 6.3.3astro (npm): 6.3.3

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
withastroastrobefore 6.3.36.3.3Patch availableCNA
—astro (npm)before 6.3.36.3.3Patch availableGHSA-8hv8-536x-4wqp
  • astro Vendorwithastro Affected before 6.3.3 Fixed in 6.3.3 Patch available CNA
  • astro (npm) Vendor— Affected before 6.3.3 Fixed in 6.3.3 Patch available GHSA-8hv8-536x-4wqp

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:astro:astro:*:*:*:*:*:node.js:*:*before 6.3.3Vulnerablewithastro
  • cpe:2.3:a:astro:astro:*:*:*:*:*:node.js:*:* Versions before 6.3.3 Vulnerable ·withastro

Remediation

  • Fix · CNA astro (withastro) Fixed in 6.3.3
  • Fix · GHSA-8hv8-536x-4wqp astro (npm) Fixed in 6.3.3 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-50146
  2. 2026-10-03 Alias added: GHSA-8hv8-536x-4wqp

References

Exploit 1

Advisory 1

Other 1

  • TI-2024-37142 Server source code is exposed to the public if sourcemaps are enabled CVSS 4.0HIGH 7.8
  • TI-2025-34958 Unauthorized third-party images in Astro’s _image endpoint CVSS 4.0MEDIUM 6.9
  • TI-2025-39915 Server-side request forgery in withastro astro CVSS 3.1MEDIUM 6.5
  • TI-2025-38274 Astro's `X-Forwarded-Host` is reflected with no validation CVSS 3.1MEDIUM 6.5
  • TI-2025-40102 Astro is vulnerable to Reflected XSS via the server islands feature CVSS 3.1HIGH 7.1
  • TI-2025-34548 Astro: Duplicate trailing slash feature can lead to Open Redirects CVSS 4.0MEDIUM 5.5
See all 19 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences