CVE-2026-40073Network attack vector

Service interruption via unchecked chunked request bodies

Published Apr 10, 2026 · Updated Apr 10, 2026

Resource exhaustion in SvelteKit before 2.57.1 allows remote attackers to interrupt adapter-node services with oversized chunked requests. The get_raw_body routine treats content-length as the streaming ceiling, so a chunked request without that header is not compared with BODY_SIZE_LIMIT. Exploitation requires an adapter-node deployment reachable without an independently enforced gateway limit and lets excess request data consume service resources.

CVSS severity6.3
Medium
EPSS probability0.54%
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 SvelteKit before 2.57.1 allows remote attackers to interrupt adapter-node services with oversized chunked requests. The get_raw_body routine treats content-length as the streaming ceiling, so a chunked request without that header is not compared with BODY_SIZE_LIMIT. Exploitation requires an adapter-node deployment reachable without an independently enforced gateway limit and lets excess request data consume service resources.

The record

CVE
CVE-2026-40073
Published
Apr 10, 2026
Updated
Apr 10, 2026
Vendor
Svelte
Product
SvelteKit
Classifications
CWE-770, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 10, 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=< 2.57.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Svelte · SvelteKitversion=< 2.57.1

Published CVSS scores

6.3GitHub, Inc.CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.002Service Exhaustion

Public exploit references

No public exploit references are available in this record.

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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