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SvelteApplication

CVE-2026-27119

MEDIUM · 5.4 CVSS v3.1 Published 2026-02-20
Fix available
A fix is available. Upgrade to 5.51.5 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
svelte performance oriented web framework. From 5.39.3, <=5.51.4, 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. This vulnerability is fixed in 5.51.5.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Svelte versions 5.39.3 through 5.51.4 contain a server-side rendering vulnerability in the <option> element where content is not properly escaped, allowing HTML injection in SSR output. This is a stored XSS vector affecting only SSR-rendered pages, while client-side rendering remains unaffected.

MitigationUpgrade Svelte to version 5.51.5 or later to receive the patch for proper HTML escaping in SSR <option> element content.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
SvelteApplication
Affected:>= 5.39.3, < 5.51.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Svelte version
    Check your package.json or run `npm list svelte` or `yarn list svelte` to see the installed version
    Affected if Version is >= 5.39.3 and < 5.51.5
  2. Confirm SSR is in use
    Search your codebase for server-side rendering setup: look for files using `render` from `@sveltejs/kit`, `svelte/server`, or SSR configuration in your build setup
    Affected if Your application uses server-side rendering to generate HTML output
  3. Locate option elements in components
    Search your Svelte component files (.svelte) for `<option>` tags containing dynamic content using {} syntax, particularly in select elements
    Affected if Components contain <option> elements with dynamic content like `{variable}` or `{expression}` that gets rendered server-side
  4. Inspect SSR output for unescaped HTML
    Temporarily add logging to your SSR render function to inspect the HTML output, or view the page source of a SSR-rendered page containing a select dropdown and check if option values contain raw unescaped HTML characters like <, >, or &
    Affected if SSR-rendered HTML shows raw HTML in option element content instead of escaped entities like &lt; or &gt;

You are affected if your Svelte version is between 5.39.3 and 5.51.4 AND you use SSR AND your components include dynamic content inside <option> elements that renders unescaped HTML in the server output.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.51.5 or later
Fixed in 5.51.5
Interim mitigation

Upgrade Svelte to version 5.51.5 or later to receive the patch for proper HTML escaping in SSR <option> element content.

Recommended fix High confidence

5.51.5

  1. Check the current Svelte version in your package.json file
  2. Update the Svelte version to 5.51.5 in package.json (change the version number for the 'svelte' dependency)
  3. Run 'npm install' (or 'yarn install' / 'pnpm install') to install the updated package
  4. Verify the installation completed successfully by checking the installed version
  5. Test your application, specifically focusing on server-side rendering (SSR) functionality to confirm the fix works and no regressions were introduced
Caveat Upgrading across multiple minor versions may introduce breaking changes; review the Svelte changelog for versions between your current version and 5.51.5

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Svelte Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-27119 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data