CVE-2026-27729Public exploitNetwork attack vector

Unauthenticated crash via unbounded action body buffering

Published Feb 24, 2026 · Updated Feb 24, 2026

Resource exhaustion in Astro 9.0.0 through 9.5.3 allows remote attackers to crash SSR standalone servers via oversized action POSTs. Astro's server action request parser buffers JSON or FormData bodies entirely in memory without a default size limit before validation. Exposure requires an on-demand rendered site using server actions with the Node adapter in standalone mode; no authentication is required, and repeated requests can sustain a crash-restart loop.

CVSS severity5.9
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Astro 9.0.0 through 9.5.3 allows remote attackers to crash SSR standalone servers via oversized action POSTs. Astro's server action request parser buffers JSON or FormData bodies entirely in memory without a default size limit before validation. Exposure requires an on-demand rendered site using server actions with the Node adapter in standalone mode; no authentication is required, and repeated requests can sustain a crash-restart loop.

The record

CVE
CVE-2026-27729
Published
Feb 24, 2026
Updated
Feb 24, 2026
Vendor
Astro Technology Company
Product
Astro
Classifications
CWE-770, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 9.0.0, < 9.5.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Astro Technology Company · Astroversion=>= 9.0.0, < 9.5.4

Published CVSS scores

5.9GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.004Application or System Exploitation DoS

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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