What is CVE-2025-55303?

CVE-2025-55303 is a medium-severity vulnerability in Astro, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2025-08-19.

How severe is CVE-2025-55303?

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

Is CVE-2025-55303 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XSS in Astro

CVE-2025-55303

Astro is a web framework for content-driven websites. In versions of astro before 5.13.2 and 4.16.18, the image optimization endpoint in projects deployed with on-demand rendering allows images from unauthorized third-party domains to be s…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.006 (46.5th 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

Astro
Withastro Astro — versions >= 5.0.0-alpha.0, < 5.13.2, < 4.16.18

Weakness classification (CWE)

Public proof-of-concept exploits

fkie-cad/nvd-json-data-feeds

References

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

Frequently asked questions

What is CVE-2025-55303?: CVE-2025-55303 is a medium-severity vulnerability in Astro, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2025-08-19.
How severe is CVE-2025-55303?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2025-55303 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.