CVE-2026-27729
Astro has memory exhaustion DoS due to missing request body size limit in Server Actions
Description
Astro is a web framework. In versions 9.0.0 through 9.5.3, Astro server actions have no default request body size limit, which can lead to memory exhaustion DoS. A single large POST to a valid action endpoint can crash the server process on memory-constrained deployments. On-demand rendered sites built with Astro can define server actions, which automatically parse incoming request bodies (JSON or FormData). The body is buffered entirely into memory with no size limit — a single oversized request is sufficient to exhaust the process heap and crash the server. Astro's Node adapter (`mode: 'standalone'`) creates an HTTP server with no body size protection. In containerized environments, the crashed process is automatically restarted, and repeated requests cause a persistent crash-restart loop. Action names are discoverable from HTML form attributes on any public page, so no authentication is required. The vulnerability allows unauthenticated denial of service against SSR standalone deployments using server actions. A single oversized request crashes the server process, and repeated requests cause a persistent crash-restart loop in containerized environments. Version 9.5.4 contains a fix.
INFO
Published Date :
Feb. 24, 2026, 1:16 a.m.
Last Modified :
Feb. 25, 2026, 3:19 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Astro to version 9.5.4 or later.
- Configure request body size limits in your server adapter.
- Implement rate limiting on action endpoints.
- Monitor server memory usage and response times.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-27729.
| URL | Resource |
|---|---|
| https://github.com/withastro/astro/commit/522f880b07a4ea7d69a19b5507fb53a5ed6c87f8 | Patch |
| https://github.com/withastro/astro/pull/15564 | Issue Tracking |
| https://github.com/withastro/astro/releases/tag/%40astrojs%2Fnode%409.5.4 | Product Release Notes |
| https://github.com/withastro/astro/security/advisories/GHSA-jm64-8m5q-4qh8 | Exploit Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-27729 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-27729
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-27729 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-27729 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Feb. 25, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CPE Configuration OR *cpe:2.3:a:astro:@astrojs/node:*:*:*:*:*:node.js:*:* versions from (including) 9.0.0 up to (excluding) 9.5.4 Added Reference Type GitHub, Inc.: https://github.com/withastro/astro/commit/522f880b07a4ea7d69a19b5507fb53a5ed6c87f8 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/withastro/astro/pull/15564 Types: Issue Tracking Added Reference Type GitHub, Inc.: https://github.com/withastro/astro/releases/tag/%40astrojs%2Fnode%409.5.4 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/withastro/astro/security/advisories/GHSA-jm64-8m5q-4qh8 Types: Exploit, Third Party Advisory -
New CVE Received by [email protected]
Feb. 24, 2026
Action Type Old Value New Value Added Description Astro is a web framework. In versions 9.0.0 through 9.5.3, Astro server actions have no default request body size limit, which can lead to memory exhaustion DoS. A single large POST to a valid action endpoint can crash the server process on memory-constrained deployments. On-demand rendered sites built with Astro can define server actions, which automatically parse incoming request bodies (JSON or FormData). The body is buffered entirely into memory with no size limit — a single oversized request is sufficient to exhaust the process heap and crash the server. Astro's Node adapter (`mode: 'standalone'`) creates an HTTP server with no body size protection. In containerized environments, the crashed process is automatically restarted, and repeated requests cause a persistent crash-restart loop. Action names are discoverable from HTML form attributes on any public page, so no authentication is required. The vulnerability allows unauthenticated denial of service against SSR standalone deployments using server actions. A single oversized request crashes the server process, and repeated requests cause a persistent crash-restart loop in containerized environments. Version 9.5.4 contains a fix. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-770 Added Reference https://github.com/withastro/astro/commit/522f880b07a4ea7d69a19b5507fb53a5ed6c87f8 Added Reference https://github.com/withastro/astro/pull/15564 Added Reference https://github.com/withastro/astro/releases/tag/%40astrojs%2Fnode%409.5.4 Added Reference https://github.com/withastro/astro/security/advisories/GHSA-jm64-8m5q-4qh8