Quick answers
- Is CVE-2026-82257 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-82257 being exploited in the wild.
- How severe is CVE-2026-82257?
- Medium severity, with a CVSS score of 4.3, published 28 August 2026.
- Which products and versions are affected?
- @sveltejs/kit (npm) SEMVER:introduced=0,fixed=2.69.1; SvelteKit <=2.69.0.
- Is there a fix for CVE-2026-82257?
- Yes. @sveltejs/kit (npm): upgrade to 2.69.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-82257 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-82257?
- Check whether you run @sveltejs/kit (npm) or SvelteKit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- @sveltejs/kit (npm): upgrade to 2.69.1 or later
npm install @sveltejs/kit@2.69.1
Technical details
This vulnerability is a prototype pollution flaw (CWE-1321) in SvelteKit's remote form function handler. When processing file input deletion in forms, the code fails to safely handle user-controlled file input names that contain prototype-polluting paths like "__proto__" or "constructor.prototype". An attacker can craft a form submission with a specially-named file input to inject properties into Object.prototype, potentially removing methods from built-in objects. The attack requires network access and user interaction (form submission), and affects SvelteKit versions <= 2.69.0. The issue is patched in versions 2.69.1 and 3.0.0-next.7 by using safe property deletion mechanisms already employed elsewhere in the codebase.
Affected products
- Svelte SvelteKit <=2.69.0
Identifiers
- CVE-2026-82257
- GHSA-866w-xmhq-wj7x
Timeline
- 2026-07-24: disclosed
- 2026-07-24: patched: Patched in version 2.69.1 and 3.0.0-next.7