CVE-2026-22803Network attack vector

Memory exhaustion via eager remote-form buffer allocation

Published Jan 15, 2026 · Updated Jan 15, 2026

Memory exhaustion in SvelteKit 2.49.0 through 2.49.4 allows remote attackers to crash servers via crafted remote-form requests. The deserialize_binary_form path trusts the header's data-length value and eagerly allocates an ArrayBuffer before the declared body arrives. Exploitation requires experimental.remoteFunctions, a reachable form remote endpoint, repeated unauthenticated connections, and stalled request bodies; memory exhaustion can crash the server process.

CVSS severity8.2
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory exhaustion in SvelteKit 2.49.0 through 2.49.4 allows remote attackers to crash servers via crafted remote-form requests. The deserialize_binary_form path trusts the header's data-length value and eagerly allocates an ArrayBuffer before the declared body arrives. Exploitation requires experimental.remoteFunctions, a reachable form remote endpoint, repeated unauthenticated connections, and stalled request bodies; memory exhaustion can crash the server process.

The record

CVE
CVE-2026-22803
Published
Jan 15, 2026
Updated
Jan 15, 2026
Vendor
Svelte
Product
SvelteKit
Classifications
CWE-770, CWE-789, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 15, 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=>= 2.49.0, < 2.49.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Svelte · SvelteKitversion=>= 2.49.0, < 2.49.5

Published CVSS scores

8.2GitHubCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
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 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
CWE-789Memory Allocation with Excessive Size Value
T1499.004Application or System Exploitation

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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