CVE-2026-42599Cross-site scripting via spread attributes in Svelte SSR
Updated under an hour ago ()
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It affects sveltejs svelte and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 5.1 MEDIUM (v4.0, CNA)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
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Jun 9, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
sveltejs svelte sveltejs:svelte (from the name) | before 5.55.7 | CNA record |
svelte svelte svelte:svelte | before 5.55.7 | NVD |
References
- https://github.com/sveltejs/svelte/security/advisories/GHSA-pr6f-5x2q-rwfpx-refsource-confirm, vendor-advisory
- https://github.com/sveltejs/svelte/releases/tag/svelte%405.55.7x-refsource-misc, release-notes
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.