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.
CVE-2025-55303
This medium-severity CVE scores 6.1 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 68% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.1
- EG Score
- 6.1(medium)
- EG Risk
- —
- EPSS
- 46.7%
- KEV
- Not listed
Published
August 19, 2025
Last Modified
November 25, 2025
References (3)
- security-advisories@githubhttps://github.com/withastro/astro/commit/4d16de7f95db5d1ec1ce88610d2a95e606e83820
- security-advisories@githubhttps://github.com/withastro/astro/security/advisories/GHSA-xf8x-j4p2-f749
- 134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/withastro/astro/security/advisories/GHSA-xf8x-j4p2-f749
Affected Packages
(2 across 1 ecosystem)
npm(2)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| astro | — | 4.16.19 | — |
| @astrojs/node | — | 9.1.1 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 43× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
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- 2026-05-30 00:11 UTCEG score recompute
- 2026-05-29 13:44 UTCEPSS rescore
Publicly available exploits
(1 reference)Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.
- Nucleihttp/cves/2025/CVE-2025-55303.yamlFirst seen Jan 1, 2025
Astro - Unauthorized Third-Party Image Access
Open source ↗
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2025-55303?
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Dependency Blast Radius
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