8.7

CVE-2026-82259: SvelteKit 2.49.0 before 2.53.3 Denial of Service via form

Analyzed
AliasesGHSA-fpg4-jhqr-589c
Published 28-08-2026Last modified 08-10-2026

Vulnerability summary

CVE-2026-82259 is a high (CVSS 8.7) Deserialization of Untrusted Data vulnerability in svelte sveltekit. EPSS estimates a 0.53% chance of exploitation in the next 30 days, higher than 45% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 8.7 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
8.7/10
010
High · v4.0 (CVE.org)
EPSS score
0.53%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 28-08-2026
    PublishedVulnerability first disclosed.
  2. 08-10-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

5 scores · 3 sources · 2 versions

EPSS trend

Probability

0.53%

Chance of exploitation in the next 30 days

Percentile

45%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.53% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

@sveltejs1 product
  • kit≥ 2.49.0, < 2.53.3
Svelte1 product
Sveltejs1 product
  • kit≥ 2.49.0, < 2.53.3

3 vendors · 3 products

References

5 links