CVE & CISA-KEV Catalog

CVE-2026-42599

MEDIUM
6.1
CVSS v3
NVD

Description

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.

How to fix

Remediation Available
svelteNVD
Affected:< 5.55.7Fixed in:5.55.7CVE-2026-42599derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeChanged

Impact

ConfidentialityLow
IntegrityLow
AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.17%probability of exploitation in 30 days
6thpercentile

Low risk: more likely to be exploited than 6% of all known CVEs.

References

Vendor Advisory1
Release Notes1

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-11022Medium6.999%-Fix
CVE-2019-3929Critical9.899%KEVFix
CVE-2020-9496Medium6.199%--
CVE-2023-28341Medium6.199%-Fix
CVE-2018-12998Medium6.198%--
CVE-2025-4123High7.698%-Fix
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Markdown

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HTML

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-11.