@sveltejs/kit vulnerable to XSS on dev mode 404 page

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2024-53261: 0.35% estimated exploitation activity in the next 30 days; percentile 28.68 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary "Unsanitized input from the request URL flows into end, where it is used to render an HTML page returned to the user. This may result in a Cross-Site Scripting attack (XSS)." Details Source of potentially tainted data is in packages/kit/src/exports/vite/dev/index.js, line 437. This potentially tainted data is passed through a number of steps (which I could detail if you'd like) all the way down to line 91 in packages/kit/src/exports/vite/utils.js, which performs an operation that Snyk believes an attacker shouldn't be allowed to manipulate. Another source of potentially tainted data (according to Snyk) comes from ‎packages/kit/src/exports/vite/utils.js, line 30, col 30 (i.e., the url property of req). This potentially tainted data is passed through a number of steps (which I could detail if you'd like) all the way down line 91 in packages/kit/src/exports/vite/utils.js, which performs an operation that Snyk believes an attacker shouldn't be allowed to manipulate. PoC Not…

Published by the source

25 Nov 2024, 15:33 UTC

Last modified by the source

22 Jan 2025, 20:54 UTC

Source last checked

26 Oct 2026, 12:31 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-rjjv-87mx-6x3h

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-rjjv-87mx-6x3h

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# Patch Next advisory brief: CVE-2024-53261

Advisory: @sveltejs/kit vulnerable to XSS on dev mode 404 page
IDs: CVE-2024-53261, GHSA-rjjv-87mx-6x3h
Record: https://patchnext.com/advisories/cve-2024-53261 (revision 2, source checked 26 Oct 2026, 12:31 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated (CVSS 0.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @sveltejs/kit 2.8.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @sveltejs/kit: affected < 2.8.3; fixed in 2.8.3

## Suggested inspection (read-only)
- `npm ls @sveltejs/kit --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @sveltejs/kit.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-rjjv-87mx-6x3h (OSV record GHSA-rjjv-87mx-6x3h lists affected ranges: npm @sveltejs/kit >=0 <2.8.3 (fixed))
- Verified: https://github.com/advisories/GHSA-rjjv-87mx-6x3h (GitHub-reviewed advisory GHSA-rjjv-87mx-6x3h lists affected ranges: npm @sveltejs/kit >=0 <2.8.3)

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