What is CVE-2025-15265?

CVE-2025-15265 is a medium-severity vulnerability in Svelte, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-01-15.

How severe is CVE-2025-15265?

Medium severity. CVSS v3 base score is 6.1 out of 10.

XSS in Svelte

CVE-2025-15265

An SSR XSS exists in async hydration when attacker‑controlled keys are passed to hydratable. The key is embedded inside a <script> block without HTML‑safe escaping, allowing </script> to terminate the script and inject arbitrary JavaScript…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.003 (21.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

Affected products

Svelte — versions 5.46.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

help@fluidattacks.com (Exploit, Third Party Advisory, third-party-advisory)
help@fluidattacks.com (vendor-advisory, Third Party Advisory)

Frequently asked questions

What is CVE-2025-15265?: CVE-2025-15265 is a medium-severity vulnerability in Svelte, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-01-15.
How severe is CVE-2025-15265?: Medium severity. CVSS v3 base score is 6.1 out of 10.