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Critical, CVSS 9.0amended

XSS via prototype pollution in NodeBB

CVE-2021-43787GHSA-wx69-rvg3-x7fc

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (nodebb 1.18.5), redeploy, then verify what is actually installed.

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.

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Affected packages

  • npm nodebb

    Affected
    >= 1.15.0, < 1.18.5
    Fixed in
    1.18.5

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.0 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
EPSS
  • CVE-2021-43787: 1.32% estimated exploitation activity in the next 30 days; percentile 70.83 (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.

Impact A prototype pollution vulnerability in the uploader module allowed a malicious user to inject arbitrary data (i.e. javascript) into the DOM, theoretically allowing for an account takeover when used in conjunction with a path traversal vulnerability disclosed at the same time as this report. Patches The vulnerability has been patched as of v1.18.5. Workarounds Cherry-pick commit hash 1783f918bc19568f421473824461ff2ed7755e4c to receive this patch in lieu of a full upgrade. For more information If you have any questions or comments about this advisory: Email us at security@nodebb.org

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-wx69-rvg3-x7fc

  2. Revision 1 · created ·

    Published from osv record GHSA-wx69-rvg3-x7fc

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-2021-43787

Advisory: XSS via prototype pollution in NodeBB
IDs: CVE-2021-43787, GHSA-wx69-rvg3-x7fc
Record: https://patchnext.com/advisories/cve-2021-43787 (revision 2, source checked 26 Oct 2026, 12:17 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: nodebb 1.18.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm nodebb: affected >= 1.15.0, < 1.18.5; fixed in 1.18.5

## Suggested inspection (read-only)
- `npm ls nodebb --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 nodebb.
- 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-wx69-rvg3-x7fc (OSV record GHSA-wx69-rvg3-x7fc lists affected ranges: npm nodebb >=1.15.0 <1.18.5 (fixed))
- Verified: https://github.com/advisories/GHSA-wx69-rvg3-x7fc (GitHub-reviewed advisory GHSA-wx69-rvg3-x7fc lists affected ranges: npm nodebb >=1.15.0 <1.18.5)

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