Medium severity · published Feb 26, 2026
CVE-2026-27902
Svelte Vulnerable to XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers
5.4
CVSS
0.3%
EPSS
No
On KEV
Description
Svelte performance oriented web framework. Prior to version 5.53.5, errors from `transformError` were not correctly escaped prior to being embedded in the HTML output, causing potential HTML injection and XSS if attacker-controlled content is returned from `transformError`. Version 5.53.5 fixes the issue.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 19% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SV
svelte · sveltejs
>= 5.53.0, < 5.53.5 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27902
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-27902
Patch
https://github.com/sveltejs/svelte/commit/0298e979371bb583855c9810db79a70a551d22b9
Release Notes
https://github.com/sveltejs/svelte/releases/tag/svelte%405.53.5
Vendor Advisory
https://github.com/sveltejs/svelte/security/advisories/GHSA-qgvg-pr8v-6rr3
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