sveltejs svelte up to 5.55.6 cross site scripting

Summaryinfo

A vulnerability was found in sveltejs svelte up to 5.55.6 and classified as problematic. Affected is an unknown function. The manipulation results in cross site scripting. This vulnerability is identified as CVE-2026-42599. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in sveltejs svelte up to 5.55.6. Affected is an unknown code. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as 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. This is going to have an impact on integrity. CVE summarizes:

Svelte is a performance oriented web framework. Prior to version 5.55.7, 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. Note that this vulnerability only triggers if the user's browser has JavaScript enabled but Svelte's hydration mechanism does not reach the vulnerable element before the event fires. This issue has been patched in version 5.55.7.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-42599 since 04/29/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation needs additional levels of successful authentication. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 5.55.7 eliminates this vulnerability. The upgrade is hosted for download at github.com.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• sveltejs

Name

• svelte

Version

• 5.55.0
• 5.55.1
• 5.55.2
• 5.55.3
• 5.55.4
• 5.55.5
• 5.55.6

Website

• Product: https://github.com/sveltejs/svelte/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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