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Critical, CVSS 9.4amended

Convict has prototype pollution via load(), loadFile(), and schema initialization

CVE-2026-33863GHSA-hf2r-9gf9-rwch

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (convict 6.2.5), 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 convict

    Affected
    <= 6.2.4
    Fixed in
    6.2.5

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
9.4 · CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H · score source
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Impact Two unguarded prototype pollution paths exist, not covered by previous fixes: 1. config.load() / config.loadFile() — overlay() recursively merges config data without checking for forbidden keys. Input containing proto or constructor.prototype (e.g. from a JSON file) causes the recursion to reach Object.prototype and write attacker-controlled values onto it. 2. Schema initialization — passing a schema with constructor.prototype. keys to convict({...}) causes default-value propagation to write directly to Object.prototype at startup. Depending on how polluted properties are consumed, impact ranges from unexpected behavior to authentication bypass or RCE. Workarounds Do not pass untrusted data to load(), loadFile(), or convict(). Resources Prior advisory: GHSA-44fc-8fm5-q62h Related issue: https://github.com/mozilla/node-convict/issues/423

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-hf2r-9gf9-rwch

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GHSA-hf2r-9gf9-rwch

  4. Revision 1 · created ·

    Published from ghsa record GHSA-hf2r-9gf9-rwch

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-2026-33863

Advisory: Convict has prototype pollution via load(), loadFile(), and schema initialization
IDs: CVE-2026-33863, GHSA-hf2r-9gf9-rwch
Record: https://patchnext.com/advisories/cve-2026-33863 (revision 4, source checked 26 Oct 2026, 12:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: convict 6.2.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm convict: affected <= 6.2.4; fixed in 6.2.5

## Suggested inspection (read-only)
- `npm ls convict --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 convict.
- 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://github.com/advisories/GHSA-hf2r-9gf9-rwch (GitHub-reviewed advisory GHSA-hf2r-9gf9-rwch lists affected ranges: npm convict >=0 <=6.2.4)
- Verified: https://osv.dev/vulnerability/GHSA-hf2r-9gf9-rwch (OSV record GHSA-hf2r-9gf9-rwch lists affected ranges: npm convict >=0 <6.2.5 (fixed))

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