CVE-2026-27122
HTML Injection in Svelte SSR via Unsanitized Tag
Publication date: 2026-02-20
Last updated on: 2026-02-23
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| svelte | svelte | to 5.51.5 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-79 | The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the Svelte web framework prior to version 5.51.5. When using the <svelte:element this={tag}> syntax in server-side rendering (SSR), the tag name provided is not validated or sanitized before being included in the HTML output. If the tag string contains unexpected or malicious characters, it can lead to HTML injection in the SSR output. This issue does not affect client-side rendering.
How can this vulnerability impact me? :
The vulnerability can allow an attacker to inject arbitrary HTML into the server-side rendered output. This could lead to security issues such as cross-site scripting (XSS) or manipulation of the rendered page content, potentially compromising the integrity and security of the web application.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, upgrade the svelte framework to version 5.51.5 or later where the issue is fixed.