CVE-2026-42567

CVE-2026-42567 affects Svelte runtimes from 5.51.5 up to 5.55.6, where an internal regex used during svelte:element tag validation can cause exponential-time processing (ReDoS) on certain tag names. The issue is triggered during the validation of , leading to significant CPU usage and potential...

EUVD-2026-35702

Svelte is a performance oriented web framework. From version 5.51.5 to before version 5.55.7, an internal regex in the Svelte runtime can take exponential time to test in . This issue has been patched in version 5.55.7...

Svelte: ReDoS in `<svelte:element>` Tag Validation

An internal regex in the Svelte runtime can take exponential time to test in . You are only vulnerable to this if you allow tags of unconstrained length. If your application only allows a predetermined list of tags or trims their length before passing them to svelte:element, you are safe...

CVE-2026-27122

svelte performance oriented web framework. Prior to 5.51.5, when using 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...

CVE-2026-27122 Svelte SSR does not validate dynamic element tag names in `<svelte:element>`

svelte performance oriented web framework. Prior to 5.51.5, when using 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...

CVE-2026-27122 Svelte SSR does not validate dynamic element tag names in `<svelte:element>`

svelte performance oriented web framework. Prior to 5.51.5, when using 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...

Cross-site Scripting (XSS)

Overview org.webjars.npm:svelte is a package for building web applications. Affected versions of this package are vulnerable to Cross-site Scripting XSS via the svelte:element tags. An attacker can inject arbitrary HTML into the server-side rendered output by supplying a crafted tag name. Details...

Cross-site Scripting (XSS)

Overview svelte is a package for building web applications. Affected versions of this package are vulnerable to Cross-site Scripting XSS via the svelte:element tags. An attacker can inject arbitrary HTML into the server-side rendered output by supplying a crafted tag name. Details Cross-site...

Svelte SSR does not validate dynamic element tag names in `<svelte:element>`

When using 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...

PT-2026-20881

Name of the Vulnerable Software and Affected Versions Svelte versions prior to 5.51.5 Description A flaw exists in Svelte where, during server-side rendering, the tag name provided to the component is not validated or sanitized before being included in the HTML output. This can lead to HTML...

PT-2026-20873

When using 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...