CVE-2026-27122
Received Received - Intake
HTML Injection in Svelte SSR via Unsanitized Tag

Publication date: 2026-02-20

Last updated on: 2026-02-23

Assigner: GitHub, Inc.

Description
svelte performance oriented web framework. Prior to 5.51.5, 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. This vulnerability is fixed in 5.51.5.
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Meta Information
Published
2026-02-20
Last Modified
2026-02-23
Generated
2026-06-16
AI Q&A
2026-02-21
EPSS Evaluated
2026-06-15
NVD
CVE-2026-27122
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
svelte svelte to 5.51.5 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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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.
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Executive Summary

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.

Impact Analysis

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.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade the svelte framework to version 5.51.5 or later where the issue is fixed.

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