Prototype Pollution in x-assign
CVE-2021-23452GHSA-4mvj-rq4v-2fxw
What to do
Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.
This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.
Affected packages
npm x-assign
- Affected
- <= 0.1.4
- Fixed in
- no fixed version recorded
Sources
- Open Source Vulnerabilities (OSV.dev), including the GitHub Advisory Database
OSV record GHSA-4mvj-rq4v-2fxw lists affected ranges: npm x-assign >=0 <=0.1.4
VerifiedObserved Structured OSV record; GitHub-reviewed advisory.
- GitHub Advisory Database and maintainer security advisories on GitHub
GitHub-reviewed advisory GHSA-4mvj-rq4v-2fxw lists affected ranges: npm x-assign >=0 <=0.1.4
VerifiedObserved Structured GitHub Advisory Database record (type=reviewed) from the GitHub REST API.
Severity and exploitation
- Exploitation
- No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
- CVSS
- 8.6 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:L
- EPSS
- CVE-2021-23452: 1.55% estimated exploitation activity in the next 30 days; percentile 75.11 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description
As published by the source; long descriptions are shortened.
This vulnerability affects all versions of package x-assign. The global proto object can be polluted using the proto object.
Dates and revisions
- Published by the source
- Last modified by the source
- Source last checked
- Revision 2 · amended ·
Amended from ghsa record GHSA-4mvj-rq4v-2fxw
- Revision 1 · created ·
Published from osv record GHSA-4mvj-rq4v-2fxw
Agent brief
Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.
# Patch Next advisory brief: CVE-2021-23452 Advisory: Prototype Pollution in x-assign IDs: CVE-2021-23452, GHSA-4mvj-rq4v-2fxw Record: https://patchnext.com/advisories/cve-2021-23452 (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: High (CVSS 8.6) Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV. Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed. ## Affected components - npm x-assign: affected <= 0.1.4 ## Suggested inspection (read-only) - `npm ls x-assign --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`. ## Supported action No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything. ## Required regression checks - Run the test suite and a production build. - Exercise the features that depend on x-assign. - 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-4mvj-rq4v-2fxw (OSV record GHSA-4mvj-rq4v-2fxw lists affected ranges: npm x-assign >=0 <=0.1.4) - Verified: https://github.com/advisories/GHSA-4mvj-rq4v-2fxw (GitHub-reviewed advisory GHSA-4mvj-rq4v-2fxw lists affected ranges: npm x-assign >=0 <=0.1.4) Commands are suggestions: review each one before running it.
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