CVE-2026-82257: sveltekit Prototype Pollution — Fix

Description

SvelteKit versions before 2.69.1 contain a prototype pollution vulnerability in remote form functions with file input fields that accept arbitrary user-controlled path names. Attackers can manipulate the deletion path to remove methods on the prototype, potentially disabling application functionality.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1321 CWE-1321

Affected Products

Vendor	Product	Versions
svelte	sveltekit	< 2.69.1

References

Advisories & Patches

https://github.com/sveltejs/kit/security/advisories/GHSA-866w-xmhq-wj7x

Other References

https://www.vulncheck.com/advisories/sveltekit-before-2.69.1-prototype-pollution-via-file-input

Frequently Asked Questions

What is CVE-2026-82257? +

SvelteKit versions before 2.69.1 contain a prototype pollution vulnerability in remote form functions with file input fields that accept arbitrary user-controlled path names. Attackers can manipulate the deletion path to remove methods on the prototype, potentially disabling application functionality. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-82257? +

CVE-2026-82257 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-82257? +

CVE-2026-82257 affects products from svelte, specifically: sveltekit. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-82257? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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