CVE-2026-40074Network attack vector

Service interruption via unhandled redirect TypeError

Published Apr 10, 2026 · Updated Apr 10, 2026

Improper exception handling in SvelteKit before 2.57.1 allows remote attackers to interrupt service through a crafted redirect. The handle server hook passes a redirect location containing HTTP-header-invalid characters into response construction, where the resulting TypeError escapes normal fatal-error handling. Exploitation requires attacker-influenced, unsanitized location data to reach redirect inside handle; affected platforms then experience a service interruption.

CVSS severity6.3
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in SvelteKit before 2.57.1 allows remote attackers to interrupt service through a crafted redirect. The handle server hook passes a redirect location containing HTTP-header-invalid characters into response construction, where the resulting TypeError escapes normal fatal-error handling. Exploitation requires attacker-influenced, unsanitized location data to reach redirect inside handle; affected platforms then experience a service interruption.

The record

CVE
CVE-2026-40074
Published
Apr 10, 2026
Updated
Apr 10, 2026
Vendor
Svelte
Product
SvelteKit
Classifications
CWE-755, T1499.004
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

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.3GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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