parse-server new anonymous user session acts as if it's created with password

Exploitation

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

CVSS

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

EPSS

• CVE-2021-39138: 0.99% estimated exploitation activity in the next 30 days; percentile 62.67 (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.

Impact Developers that use the REST API to signup users and also allow users to login anonymously. When an anonymous user is first signed up using REST, the server creates session incorrectly, particularly the authProvider field in Session class under createdWith shows the user logged in creating a password. If a developer later depends on the createdWith field to provide a different level of access between a password user and anonymous user, the server incorrectly classified the session type as being created with a password. The server currently doesn't use createdWith to make decisions on how things work internally, so if a developer isn't using createdWith directly, there's nothing to worry about. The vulnerability only affects users who depend on createdWith by using it directly. Patches Upgrade to version 4.5.1. Workarounds Don't use the createdWith Session field to make decisions if you allow anonymous login. References n/a

Published by the source

23 Aug 2021, 19:41 UTC

Last modified by the source

8 Jul 2026, 06:29 UTC

Source last checked

26 Oct 2026, 12:16 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-23r4-5mxp-c7g5

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-23r4-5mxp-c7g5

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# Patch Next advisory brief: CVE-2021-39138

Advisory: parse-server new anonymous user session acts as if it's created with password
IDs: CVE-2021-39138, GHSA-23r4-5mxp-c7g5
Record: https://patchnext.com/advisories/cve-2021-39138 (revision 2, source checked 26 Oct 2026, 12:16 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: parse-server 4.5.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm parse-server: affected < 4.5.2; fixed in 4.5.2

## Suggested inspection (read-only)
- `npm ls parse-server --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 parse-server.
- 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-23r4-5mxp-c7g5 (OSV record GHSA-23r4-5mxp-c7g5 lists affected ranges: npm parse-server >=0 <4.5.2 (fixed))
- Verified: https://github.com/advisories/GHSA-23r4-5mxp-c7g5 (GitHub-reviewed advisory GHSA-23r4-5mxp-c7g5 lists affected ranges: npm parse-server >=0 <4.5.2)

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