@astrojs/node's trailing slash handling causes open redirect issue

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

5.5 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:P · score source

EPSS

• CVE-2025-55207: 0.57% estimated exploitation activity in the next 30 days; percentile 47.35 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary Following https://github.com/withastro/astro/security/advisories/GHSA-cq8c-xv66-36gw, there's still an Open Redirect vulnerability in a subset of Astro deployment scenarios. Details Astro 5.12.8 fixed a case where https://example.com//astro.build/press would redirect to the external origin //astro.build/press. However, with the Node deployment adapter in standalone mode and trailingSlash set to "always" in the Astro configuration, https://example.com//astro.build/press still redirects to //astro.build/press. Proof of Concept 1. Create a new minimal Astro project (astro@5.12.8) 2. Configure it to use the Node adapter (@astrojs/node@9.4.0) and force trailing slashes: 3. Build the site by running astro build. 4. Run the server, e.g. with astro preview. 5. Append //astro.build/press to the preview URL, e.g. <http://localhost:4321//astro.build/press 6. The site will redirect to the external Astro Build origin. Example reproduction 1. Open this StackBlitz reproduction. 2. Open the…

Published by the source

15 Aug 2025, 16:52 UTC

Last modified by the source

15 Aug 2025, 20:55 UTC

Source last checked

26 Oct 2026, 12:37 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-9x9c-ghc5-jhw9

2. Revision 2 · amended · 24 Oct 2026

   Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-9x9c-ghc5-jhw9

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# Patch Next advisory brief: CVE-2025-55207

Advisory: @astrojs/node's trailing slash handling causes open redirect issue
IDs: CVE-2025-55207, GHSA-9x9c-ghc5-jhw9
Record: https://patchnext.com/advisories/cve-2025-55207 (revision 3, source checked 26 Oct 2026, 12:37 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @astrojs/node 9.4.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @astrojs/node: affected <= 9.4.0; fixed in 9.4.1

## Suggested inspection (read-only)
- `npm ls @astrojs/node --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @astrojs/node.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-9x9c-ghc5-jhw9 (OSV record GHSA-9x9c-ghc5-jhw9 lists affected ranges: npm @astrojs/node >=0 <9.4.1 (fixed))
- Verified: https://github.com/advisories/GHSA-9x9c-ghc5-jhw9 (GitHub-reviewed advisory GHSA-9x9c-ghc5-jhw9 lists affected ranges: npm @astrojs/node >=0 <=9.4.0)

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