CVE-2026-42567 Details
Description
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 <svelte:element this={tag}></svelte:element>. This issue has been patched in version 5.55.7.
A denial-of-service vulnerability has been identified in the Svelte web framework, specifically in versions 5.51.5 prior to 5.55.7. The issue arises from an internal regular expression in the Svelte runtime that can cause exponential time complexity when processing tags of unconstrained length within the `<svelte:element>` tag. This vulnerability can lead to significant performance degradation. However, applications that restrict tag lengths or allow only a predetermined list of tags are not affected.
Users can upgrade to Svelte version 5.55.7, where this vulnerability has been patched.
Metrics
CVSS 4.0 Severity and Vector Strings:
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jun 9, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/sveltejs/svelte/releases/tag/svelte%405.55.7 | [email protected] | ProductRelease Notes |
| https://github.com/sveltejs/svelte/security/advisories/GHSA-9rmh-mm8f-r9h6 | [email protected] | Vendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-1333 | Inefficient Regular Expression Complexity | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| svelte svelte | >= 5.51.5, < 5.55.7 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 23, 2026 | CVE Translated | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 11, 2026 | Initial Analysis | [email protected] |
| Jun 9, 2026 | New CVE Received | [email protected] |