Svelte SSR vulnerable to cross-site scripting via spread attributes
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 is similar to but different from CVE-2026-27121.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | svelte | < 5.55.7 | 5.55.7 |
References
- CVSS vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
svelte- Disclosed
- 14.05.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-pr6f-5x2q-rwfp - CC BY 4.0
Vulnerability history: svelte
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 14
- First → latest
- 07.2022 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 13
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 12
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Svelte SSR vulnerable to cross-site scripting via spread attributes this entry
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