CVE-2026-27902CWE-79

Svelte Vulnerable to XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers

Medium · published February 26, 2026

CVSS v4.0
5.3
EPSS
0%
Percentile
32.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
5.3 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:H/SI:H/SA:N
EPSS
0.00396 · 32.7th percentile
Weakness
CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-02-26T00:58Z
EPSS history
Timeline
  • 26 FEB 00:58Z
    Svelte Vulnerable to XSS via HTML Comment Injection in SSR Error Boundary Hydration Markers
    cvelistv5