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VulnerabilityPublished

CVE-2026-29772: withastro astro · Unthrottled Resource Allocation

Affects withastro astroSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 10.0.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 32% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 10.0.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade withastro astro to 10.0.0.

Affected software

ProductAffectedFixed in
withastroastroAffected
  • <10.0.0
Fixed in
  • 10.0.0
npmastropkg:npm/astroOther threatsAffected
  • <10.0.0
Fixed in
  • 10.0.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate this vulnerability, organizations should upgrade all Astro SSR applications using the Node standalone adapter to version 10.0.0 or later, where the issue is patched. If immediate upgrade is not feasible, implement network-level protections such as rate limiting and request size restrictions on the /_server-islands/[name] endpoint to prevent large or excessive POST requests. Employ Web Application Firewalls (WAFs) capable of detecting and blocking anomalous JSON payloads or unusually large request bodies. Monitor server memory usage and set process-level memory limits to detect and mitigate potential exhaustion attempts. Additionally, consider isolating Astro SSR services behind reverse proxies that can enforce stricter request validation and size limits. Regularly audit and update dependencies to ensure timely application of security patches. Finally, implement logging and alerting for unusual spikes in request sizes or server crashes to enable rapid incident response.

Description

CVE-2026-29772 is a medium-severity vulnerability in the Astro web framework versions prior to 10.0.0. The issue arises from the Server Islands POST handler, which parses the entire request body as JSON without enforcing any size limits. This allows an attacker to send a crafted payload containing many small JSON objects, causing approximately 15 times memory amplification in the V8 JavaScript engine heap. As a result, a single unauthenticated request can exhaust the server's memory and crash the process, leading to denial of service. The vulnerable endpoint is /_server-islands/[name], which is registered on all Astro SSR apps using the Node standalone adapter, regardless of component usage. The vulnerability has been patched in Astro version 10.0.0.

References

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