What is CVE-2026-27902?

CVE-2026-27902 is a medium-severity vulnerability in Svelte, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-02-26.

How severe is CVE-2026-27902?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Svelte

CVE-2026-27902

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…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.002 (13.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N.

Affected products

Svelte
Sveltejs Svelte — versions >= 5.53.0, < 5.53.5

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
security-advisories@github.com (Patch, x_refsource_MISC)
security-advisories@github.com (x_refsource_MISC, Release Notes)

Frequently asked questions

What is CVE-2026-27902?: CVE-2026-27902 is a medium-severity vulnerability in Svelte, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-02-26.
How severe is CVE-2026-27902?: Medium severity. CVSS v3 base score is 5.4 out of 10.