chore(deps): update dependency svelte to v5.51.5 [security]

[renovate]

This PR contains the following updates:

Package	Type	Update	Change	OpenSSF
svelte (source)	devDependencies	minor	5.49.1 → 5.51.5

GitHub Vulnerability Alerts

CVE-2026-27119

In certain circumstances, the server-side rendering output of an <option> element does not properly escape its content, potentially allowing HTML injection in the SSR output. Client-side rendering is not affected.

CVE-2026-27121

Versions of svelte prior to 5.51.5 are vulnerable to cross-site scripting (XSS) during server-side rendering. When using spread syntax to render attributes from untrusted data, event handler properties are included in the rendered HTML output. If an application spreads user-controlled or external data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers.

CVE-2026-27122

When using <svelte:element this={tag}> in server-side rendering, the provided tag name is not validated or sanitized before being emitted into the HTML output. If the tag string contains unexpected characters, it can result in HTML injection in the SSR output. Client-side rendering is not affected.

CVE-2026-27125

In server-side rendering, attribute spreading on elements (e.g. <div {...attrs}>) enumerates inherited properties from the object's prototype chain rather than only own properties. In environments where Object.prototype has already been polluted — a precondition outside of Svelte's control — this can cause unexpected attributes to appear in SSR output or cause SSR to throw errors. Client-side rendering is not affected.

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Release Notes

sveltejs/svelte (svelte)

v5.51.5

Compare Source

Patch Changes

• fix: check to make sure svelte:element tags are valid during SSR (73098bb26c6f06e7fd1b0746d817d2c5ee90755f)

• fix: misc option escaping and backwards compatibility (#​17741)

• fix: strip event handlers during SSR (a0c7f289156e9fafaeaf5ca14af6c06fe9b9eae5)

• fix: replace usage of for in with for of Object.keys (f89c7ddd7eebaa1ef3cc540400bec2c9140b330c)

• fix: always escape option body in SSR (f7c80da18c215e3727c2a611b0b8744cc6e504c5)

• chore: upgrade devalue (#​17739)

v5.51.4

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Patch Changes

• chore: proactively defer effects in pending boundary (#​17734)

• fix: detect and error on non-idempotent each block keys in dev mode (#​17732)

v5.51.3

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Patch Changes

• fix: prevent event delegation logic conflicting between svelte instances (#​17728)

• fix: treat CSS attribute selectors as case-insensitive for HTML enumerated attributes (#​17712)

• fix: locate Rollup annontaion friendly to JS downgraders (#​17724)

• fix: run effects in pending snippets (#​17719)

v5.51.2

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Patch Changes

• fix: take async into consideration for dev delegated handlers (#​17710)

• fix: emit state_referenced_locally warning for non-destructured props (#​17708)

v5.51.1

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Patch Changes

• fix: don't crash on undefined document.contentType (#​17707)

• fix: use symbols for encapsulated event delegation (#​17703)

v5.51.0

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Minor Changes

• feat: Use TrustedTypes for HTML handling where supported (#​16271)

Patch Changes

• fix: sanitize template-literal-special-characters in SSR attribute values (#​17692)

• fix: follow-up formatting in print() — flush block-level elements into separate sequences (#​17699)

• fix: preserve delegated event handlers as long as one or more root components are using them (#​17695)

v5.50.3

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Patch Changes

• fix: take into account nodeName case sensitivity on XHTML pages (#​17689)

• fix: render multiple and selected attributes as empty strings for XHTML compliance (#​17689)

• fix: always lowercase HTML elements, for XHTML compliance (#​17664)

• fix: freeze effects-inside-deriveds when disconnecting, unfreeze on reconnect (#​17682)

• fix: propagate $effect errors to <svelte:boundary> (#​17684)

v5.50.2

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Patch Changes

• fix: resolve effect_update_depth_exceeded when using bind:value on <select> with derived state in legacy mode (#​17645)

• fix: don't swallow DOMException when media.play() fails in bind:paused (#​17656)

• chore: provide proper public type for parseCss result (#​17654)

• fix: robustify blocker calculation (#​17676)

• fix: reduce if block nesting (#​17662)

v5.50.1

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Patch Changes

• fix: render boolean attribute values as empty strings for XHTML compliance (#​17648)

• fix: prevent async render tag hydration mismatches (#​17652)

v5.50.0

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Minor Changes

• feat: allow use of createContext when instantiating components programmatically (#​17575)

Patch Changes

• fix: ensure infinite effect loops are cleared after flushing (#​17601)

• fix: allow {#key NaN} (#​17642)

• fix: detect store in each block expression regardless of AST shape (#​17636)

• fix: treat <menu> like <ul>/<ol> for a11y role checks (#​17638)

• fix: add vite-ignore comment inside dynamic crypto import (#​17623)

• chore: wrap JSDoc URLs in @see and @link tags (#​17617)

• fix: properly hydrate already-resolved async blocks (#​17641)

• fix: emit each_key_duplicate error in production (#​16724)

• fix: exit resolved async blocks on correct node when hydrating (#​17640)

v5.49.2

Compare Source

Patch Changes

• chore: remove SvelteKit data attributes from elements.d.ts (#​17613)

• fix: avoid erroneous async derived expressions for blocks (#​17604)

• fix: avoid Cloudflare warnings about not having the "node:crypto" module (#​17612)

• fix: reschedule effects inside unskipped branches (#​17604)

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