CVE-2026-42567
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk34th percentile - higher than 34% of all known CVEs
Summary
Svelte framework versions 5.51.5 through 5.55.6 have a ReDoS vulnerability in <svelte:element this={tag}></svelte:element>. An internal regex can take exponential time to test.
Risk Assessment
An attacker can cause significant slowdown or hang of the application by providing a crafted tag, leading to denial of service.
Recommendation
Update Svelte to version 5.55.7 or later.
Other vulnerabilities in Svelte
See all- CVE-2026-42599Medium
Svelte prior to version 5.55.7 contains a vulnerability where, when using spread syntax to render attributes from untrusted data, event handlers are included in the rendered HTML output. If an application spreads user-controlled data as element attributes, an attacker can inject malicious event handlers that execute in victims' browsers. The vulnerability only triggers if the user's browser has JavaScript enabled and Svelte's hydration mechanism does not reach the vulnerable element before the event fires.
- CVE-2026-42573Medium
Svelte prior to version 5.55.7 is vulnerable to DOM clobbering of its internal framework state on elements, potentially leading to XSS attacks.
Original NVD description (English source)
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.