@apostrophecms/file pretty-URL Vulnerable to Unauthenticated SSRF via Host header

Exploitation

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

CVSS

3.7 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS

• CVE-2026-53607: 0.27% estimated exploitation activity in the next 30 days; percentile 19.91 (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 When prettyUrls: true is enabled on @apostrophecms/file (a documented SEO feature for serving uploaded files at clean URLs), the public pretty-URL handler builds the upstream URL using the raw Host HTTP request header: That URL is then fetch'ed and the response body + headers are streamed straight back to the requester. Because Host is fully attacker-controlled, an unauthenticated remote attacker can pivot the apostrophe process to issue outbound HTTP requests against any host it can reach on the private network. The path component is constrained to /uploads/attachments/<cuid-<slug.<ext (built from a local-DB lookup), which keeps the impact narrow: cross-instance data exfiltration is neutralised by cuid uniqueness, but blind-SSRF residuals remain (network-topology mapping via response-code / timing differences and verbose proxy/WAF 404 body disclosure). Verified on apostrophe@4.30.0 (latest); no fixed release exists. - Affected: apostrophe <= 4.30.0 when @apostrophecms/file…

Published by the source

31 Jul 2026, 21:51 UTC

Last modified by the source

31 Jul 2026, 22:00 UTC

Source last checked

26 Oct 2026, 13:00 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-34pj-2622-jvxq

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-34pj-2622-jvxq

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# Patch Next advisory brief: CVE-2026-53607

Advisory: @apostrophecms/file pretty-URL Vulnerable to Unauthenticated SSRF via Host header
IDs: CVE-2026-53607, GHSA-34pj-2622-jvxq
Record: https://patchnext.com/advisories/cve-2026-53607 (revision 2, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: apostrophe 4.31.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm apostrophe: affected <= 4.30.0; fixed in 4.31.0

## Suggested inspection (read-only)
- `npm ls apostrophe --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 apostrophe.
- 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-34pj-2622-jvxq (OSV record GHSA-34pj-2622-jvxq lists affected ranges: npm apostrophe >=0 <4.31.0 (fixed))
- Verified: https://github.com/advisories/GHSA-34pj-2622-jvxq (GitHub-reviewed advisory GHSA-34pj-2622-jvxq lists affected ranges: npm apostrophe >=0 <=4.30.0)

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