How severe is CVE-2026-82259?

CVE-2026-82259 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-82259 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-82259?

CVE-2026-82259 affects Svelte Sveltekit. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-82259?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-82259 published?

CVE-2026-82259 was published on 2026-08-28 and last updated on 2026-08-31.

CVE-2026-82259

CVE-2026-82259 is a high-severity vulnerability in Svelte Sveltekit with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Svelte Sveltekit
Published: 2026-08-28
Last modified: 2026-08-31

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.

Frequently asked questions

What is CVE-2026-82259?: 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.
How severe is CVE-2026-82259?: CVE-2026-82259 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-82259 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-82259?: CVE-2026-82259 affects Svelte Sveltekit. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-82259?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-82259 published?: CVE-2026-82259 was published on 2026-08-28 and last updated on 2026-08-31.

References

Affected products (1)

cpe:2.3:a:svelte:sveltekit:*:*:*:*:*:node.js:*:*

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