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Critical, CVSS 9.8amended

Prototype Pollution in express-fileupload

CVE-2020-7699GHSA-9wcg-jrwf-8gg7

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (express-fileupload 1.1.9), 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

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
9.8 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
  • CVE-2020-7699: 4.76% estimated exploitation activity in the next 30 days; percentile 91.91 (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 affects the package express-fileupload before 1.1.8. If the parseNested option is enabled, sending a corrupt HTTP request can lead to denial of service or arbitrary code execution.

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

    Amended from ghsa record GHSA-9wcg-jrwf-8gg7

  2. Revision 1 · created ·

    Published from osv record GHSA-9wcg-jrwf-8gg7

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-2020-7699

Advisory: Prototype Pollution in express-fileupload
IDs: CVE-2020-7699, GHSA-9wcg-jrwf-8gg7
Record: https://patchnext.com/advisories/cve-2020-7699 (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: Critical (CVSS 9.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: express-fileupload 1.1.9. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm express-fileupload: affected < 1.1.9; fixed in 1.1.9

## Suggested inspection (read-only)
- `npm ls express-fileupload --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 express-fileupload.
- 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-9wcg-jrwf-8gg7 (OSV record GHSA-9wcg-jrwf-8gg7 lists affected ranges: npm express-fileupload >=0 <1.1.9 (fixed))
- Verified: https://github.com/advisories/GHSA-9wcg-jrwf-8gg7 (GitHub-reviewed advisory GHSA-9wcg-jrwf-8gg7 lists affected ranges: npm express-fileupload >=0 <1.1.9)

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