What is CVE-2026-27829?

CVE-2026-27829 is a medium-severity vulnerability in Astro \@Astrojs\/node, classified under Server-Side Request Forgery (SSRF). CVSS score: 6.5/10. Published 2026-02-26.

How severe is CVE-2026-27829?

Medium severity. CVSS v3 base score is 6.5 out of 10.

SSRF in Astro \@Astrojs\/node

CVE-2026-27829

Astro is a web framework. In versions 9.0.0 through 9.5.3, a bug in Astro's image pipeline allows bypassing `image.domains` / `image.remotePatterns` restrictions, enabling the server to fetch content from unauthorized remote hosts. Astro provides an `inferSize` option that fetches remote images at render time to determine their dimensions. Remote image fetches are intended to be restricted to domains the site developer has manually authorized (using the `image.domains` or `image.remotePatterns` options). However, when `inferSize` is used, no domain validation is performed — the image is fetched from any host regardless of the configured restrictions. An attacker who can influence the image URL (e.g., via CMS content or user-supplied data) can cause the server to fetch from arbitrary hosts. This allows bypassing `image.domains` / `image.remotePatterns` restrictions to make server-side requests to unauthorized hosts. This includes the risk of server-side request forgery (SSRF) against internal network services and cloud metadata endpoints. Version 9.5.4 fixes the issue.

Vulnerability class: SSRF (Server-Side Request Forgery)

Published 2026-02-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L.

EPSS exploit prediction

EPSS: 0.004 (35.1th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001

Affected products

Astro \@Astrojs\/node
Withastro Astro — versions >= 9.0.0, < 9.5.4

Weakness classification (CWE)

CWE-918 — Server-Side Request Forgery (SSRF)

References

github.com/withastro/astro/security/advisories/GHSA-cj9f-h6r6-4cx2 (Exploit, Vendor Advisory)
github.com/withastro/astro/commit/e01e98b063e90d274c42130ec2a60cc0966622c9 (Patch)

Frequently asked questions

What is CVE-2026-27829?: CVE-2026-27829 is a medium-severity vulnerability in Astro \@Astrojs\/node, classified under Server-Side Request Forgery (SSRF). CVSS score: 6.5/10. Published 2026-02-26.
How severe is CVE-2026-27829?: Medium severity. CVSS v3 base score is 6.5 out of 10.