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CVE-2026-33863 — convict

CVE-2026-33863 is a remote code execution vulnerability in convict. A fix is available for convict — see the affected versions and patch details below.

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

Published
Mar 26, 2026
Updated
Mar 26, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Mar 26, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

927other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
convictnpm
858Kdownloads / week

Description

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

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmconvictall versions6.2.5npm install convict@6.2.5

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for convict, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update convict to 6.2.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33863 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-33863 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-33863. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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
O3 Security · Impact-Aware SCA

Is CVE-2026-33863 in your dependencies?

O3 Security finds CVE-2026-33863 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works
CVE-2026-33863: convict RCE | O3 Security