CVE-2026-29772 Details
Description
Astro is a web framework. Prior to version 10.0.0, Astro's Server Islands POST handler buffers and parses the full request body as JSON without enforcing a size limit. Because JSON.parse() allocates a V8 heap object for every element in the input, a crafted payload of many small JSON objects achieves ~15x memory amplification (wire bytes to heap bytes), allowing a single unauthenticated request to exhaust the process heap and crash the server. The /_server-islands/[name] route is registered on all Astro SSR apps regardless of whether any component uses server:defer, and the body is parsed before the island name is validated, so any Astro SSR app with the Node standalone adapter is affected. This issue has been patched in version 10.0.0.
A denial-of-service vulnerability has been identified in Astro's Server Islands feature, present in versions prior to 10.0.0. The issue arises because the POST handler for Server Islands routes buffers and parses the entire request body as JSON without any size limit. This lack of restriction allows an unauthenticated request to send a payload of numerous small JSON objects, leading to significant memory amplification and causing the server to crash. The vulnerability affects all Astro SSR applications using the Node standalone adapter, as the problematic route is registered by default, regardless of whether server:defer components are used.
Users can upgrade to Astro version 10.0.0 or later to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 24, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/withastro/astro/security/advisories/GHSA-3rmj-9m5h-8fpv | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| astro @astrojs/node | >= 9.0.0, < 10.0.0 |
CPE
Remediation
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Change History
4 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Mar 25, 2026 | Initial Analysis | [email protected] |
| Mar 24, 2026 | New CVE Received | [email protected] |