CVE-2020-28499
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedAll versions of package merge are vulnerable to Prototype Pollution via _recursiveMerge .
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceThe 'merge' npm package versions contain a prototype pollution vulnerability in the _recursiveMerge function. Attackers can manipulate the __proto__ or constructor properties during object merging operations, potentially gaining control over the object's prototype chain and executing arbitrary code or causing denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data< 2.1.1CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify merge package installationRun 'npm list merge' in your project root to list the merge package and its versionAffected if The merge package is installed with a version less than 2.1.1
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Verify the installed version against the vulnerable rangeCheck the version output from npm list or inspect package.json and package-lock.json for the merge entryAffected if The installed version is less than 2.1.1 (e.g., 2.1.0, 2.0.0, 1.x.x, etc.)
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Locate code that imports or requires mergeSearch your codebase for require('merge') or import statements referencing the merge package, and review where merge functions are invokedAffected if Your codebase imports and calls functions from the merge package (such as merge(), merge.recursive(), or object merging utilities)
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Determine if user-controlled input reaches merge operationsTrace data flow from request parameters, API inputs, or file uploads to merge function calls. Inspect the objects passed as arguments to mergeAffected if Untrusted or user-supplied data (especially objects with __proto__ or constructor properties) can be passed directly to merge functions without prior sanitization
You are affected if the merge npm package version is below 2.1.1 AND your code uses merge functions with objects that may contain __proto__ or constructor properties from untrusted sources.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped2.1.1
Update the merge package to a patched version if available, or implement input sanitization to filter out __proto__ and constructor properties before passing objects to merge functions. Consider migrating to a safer alternative if no patch is provided.
2.1.1 or later
- Identify the merge package version in your project (check package.json or package-lock.json)
- Run the appropriate package manager upgrade command to update merge to version 2.1.1 or later (e.g., npm install merge@^2.1.1, yarn upgrade merge@^2.1.1, or pnpm update merge)
- Verify the installed version meets the minimum requirement of 2.1.1
- Rebuild and test your application to ensure functionality is intact
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-28499 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-28499 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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