SvelteKit before 3.0.0 Open Redirect via Enhanced Form Actions

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

SvelteKit (@sveltejs/kit) before 3.0.0 contains an open redirect vulnerability in enhanced form actions (use:enhance) on routes accepting paths beginning with a double slash. Attackers can craft action paths starting with // that become protocol-relative URLs, causing non-redirect form results to navigate victims to attacker-controlled sites.

Source published

21 Oct 2026 00:36:34 UTC

Source modified

21 Oct 2026 15:50:38 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 4.0 · 2.1 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

CVSS 3.1 · 4.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

SvelteKit (@sveltejs/kit) before 3.0.0 contains an open redirect vulnerability in enhanced form actions (use:enhance) on routes accepting paths beginning with a double slash. Attackers can craft action paths starting with // that become protocol-relative URLs, causing non-redirect form results to navigate victims to attacker-controlled sites.

Source published

21 Oct 2026 01:17:29 UTC

Source modified

22 Oct 2026 17:39:56 UTC

Observed here

25 Oct 2026 05:17:18 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 2.1 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS 3.1 · [email protected] · Secondary · 4.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

### Impact Applications using enhanced form actions (`use:enhance`) on routes that accept paths beginning with `//`, such as catch-all routes, may be vulnerable to an open redirect. ### Patches A fix has been prepared for `@sveltejs/kit` 3.0.0. Users should upgrade to 3.0.0 or later. The fix preserves leading double slashes in action paths without generating protocol-relative URLs, restricts non-redirect action navigation to the current origin, and includes the origin when comparing action locations with the current page. ### Workarounds Reject requests whose parsed URL pathname begins with `//` before route resolution, for example in a reverse proxy or a SvelteKit `handle` hook. Alternatively, disable navigation for non-redirect enhanced form results by supplying a custom submission callback: ```svelte <form method="POST" use:enhance={() => ({ update }) => update({ navigate: false })}> <!-- form fields --> </form> ``` This applies non-redirect results to the current page instead of navigating to the action location.

Source published

23 Oct 2026 20:58:24 UTC

Source modified

23 Oct 2026 21:15:03 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Publisher rating · LOW