CVE-2026-82259

SvelteKit 2.49.0 before 2.53.3 Denial of Service via form

HIGH
7.5
CVSS Score
Published: August 28, 2026 at 10:49 AM UTC
Updated: October 8, 2026 at 04:17 PM UTC
3 products affected across 2 vendorsKitSveltekitKit

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Severity
HIGH7.5
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

SvelteKit versions from 2.49.0 through 2.53.2 (fixed in 2.53.3) contain a deserialization expansion issue in the experimental form remote function. When an application enables experimental.remoteFunctions and uses the form function to process the files array without validating files.length or individual file sizes, an attacker can submit relatively small inputs that expand into very large file arrays, leading to expensive processing and denial of service.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.49.0 ≤ v < 2.53.3
Affected range stops below 2.53.3, so it looks safe — our inference, not a vendor statement
2.49.0 ≤ v < 2.53.3*
Affected range stops below 2.53.3, so it looks safe — our inference, not a vendor statement
2.49.0 ≤ v < 2.53.32.49.0
Vendor states this is fixed in 2.53.3 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHVulnCheck
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-502

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