CVE-2025-55303

Unauthorized third-party images in Astro’s _image endpoint

MEDIUM
6.1
CVSS Score
Published: August 19, 2025 at 06:08 PM UTC
Updated: June 17, 2026 at 09:41 AM UTC
2 products affected across 2 vendorsAstroAstro

Using astro by withastro?

Get instant alerts when new vulnerabilities affect astro - before attackers find them.

Real-time alertsTrack your software stackFree plan available
Severity
MEDIUM6.1
Exploit prediction
EPSS 0.6%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.16.185.0.0 ≤ v < 5.13.2
v < 4.16.18v < 5.13.2
Affected range stops below 4.16.18, so it looks safe — our inference, not a vendor statement
Affected range stops below 5.13.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-79CWE-115

Get alerted

Stop reading CVE feeds looking for your own stack

Track the products you run and VulnTracker tells you when a new CVE affects them — with what is known about fixing it, and nothing about the rest.

Free plan, no card