How severe is CVE-2025-55303?

CVE-2025-55303 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2025-55303 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-55303?

CVE-2025-55303 affects Astro. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2025-55303?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-55303 have an EU (EUVD) identifier?

Yes. CVE-2025-55303 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25235.

When was CVE-2025-55303 published?

CVE-2025-55303 was published on 2025-08-19 and last updated on 2026-06-17.

CVE-2025-55303

CVE-2025-55303 is a medium-severity vulnerability in Astro with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v4: 6.9
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-25235
Weakness: CWE-79
Affected product: Astro
Published: 2025-08-19
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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 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.
How severe is CVE-2025-55303?: CVE-2025-55303 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2025-55303 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-55303?: CVE-2025-55303 affects Astro. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-55303?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-55303 have an EU (EUVD) identifier?: Yes. CVE-2025-55303 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25235.
When was CVE-2025-55303 published?: CVE-2025-55303 was published on 2025-08-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:astro:astro:*:*:*:*:*:node.js:*:*

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