StudioCMS S3 Storage Manager Authorization Bypass via Missing await on Async Auth Check

Exploitation

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

CVSS

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

EPSS

• CVE-2026-32101: 0.19% estimated exploitation activity in the next 30 days; percentile 9.23 (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 The S3 storage manager's isAuthorized() function is declared async (returns Promise<boolean) but is called without await in both the POST and PUT handlers. Since a Promise object is always truthy in JavaScript, !isAuthorized(type) always evaluates to false, completely bypassing the authorization check. Any authenticated user with the lowest visitor role can upload, delete, rename, and list all files in the S3 bucket. Details The isAuthorized function is typed as returning Promise<boolean in packages/studiocms/src/handlers/storage-manager/definitions.ts:88: Both context drivers implement it as async — packages/studiocms/src/handlers/storage-manager/core/effectify-astro-context.ts:32: But in the S3 storage manager, it's called without await — packages/@studiocms/s3-storage/src/s3-storage-manager.ts:200: And again at line 372 (PUT handler): isAuthorized(type) returns a Promise object. !Promise{...} is always false because a Promise is truthy. The 401 response is never returned.…

Published by the source

12 Mar 2026, 14:49 UTC

Last modified by the source

14 Mar 2026, 03:11 UTC

Source last checked

26 Oct 2026, 12:43 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-mm78-fgq8-6pgr

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-mm78-fgq8-6pgr

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# Patch Next advisory brief: CVE-2026-32101

Advisory: StudioCMS S3 Storage Manager Authorization Bypass via Missing `await` on Async Auth Check
IDs: CVE-2026-32101, GHSA-mm78-fgq8-6pgr
Record: https://patchnext.com/advisories/cve-2026-32101 (revision 2, source checked 26 Oct 2026, 12:43 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @studiocms/s3-storage 0.3.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @studiocms/s3-storage: affected <= 0.3.0; fixed in 0.3.1

## Suggested inspection (read-only)
- `npm ls @studiocms/s3-storage --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 @studiocms/s3-storage.
- 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-mm78-fgq8-6pgr (OSV record GHSA-mm78-fgq8-6pgr lists affected ranges: npm @studiocms/s3-storage >=0 <0.3.1 (fixed))
- Verified: https://github.com/advisories/GHSA-mm78-fgq8-6pgr (GitHub-reviewed advisory GHSA-mm78-fgq8-6pgr lists affected ranges: npm @studiocms/s3-storage >=0 <=0.3.0)

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