Is CVE-2025-55303 in the CISA KEV catalog?

No. CVE-2025-55303 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2025-55303?

CVE-2025-55303 has a CVSS v3 base score of 6.1 (MEDIUM).

What is the EPSS score for CVE-2025-55303?

CVE-2025-55303 has an EPSS score of 0.60% (44th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2025-55303?

Upgrade astro to 5.13.2 or later.

CVE & CISA-KEV Catalog

CVE-2025-55303

MEDIUM

6.1

CVSS v3

NVD

Description

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 served. On-demand rendered sites built with Astro include an /_image endpoint which returns optimized versions of images. A bug in impacted versions of astro allows an attacker to bypass the third-party domain restrictions by using a protocol-relative URL as the image source, e.g. /_image?href=//example.com/image.png. This vulnerability is fixed in 5.13.2 and 4.16.18.

CWE-79Cross-Site Scripting (XSS)CWE-115

How to fix

Remediation Available

astroNVD

Affected:>= 5.0.0, < 5.13.2Fixed in:5.13.2CVE-2025-55303derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeChanged

Impact

ConfidentialityLow

IntegrityLow

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.60%probability of exploitation in 30 days

44thpercentile

Moderate risk: more likely to be exploited than 44% of all known CVEs.

References

Patch1

github.com

Exploit1

github.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-11-25.