Go DriverApplication · MongoDB
CVE-2021-20329
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 · uneditedSpecific cstrings input may not be properly validated in the MongoDB Go Driver when marshalling Go objects into BSON. A malicious user could use a Go object with specific string to potentially inject additional fields into marshalled documents. This issue affects all MongoDB GO Drivers prior to and including 1.5.0.
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 confidenceA validation flaw in the MongoDB Go Driver's BSON marshalling process allows specially crafted Go objects with specific 'cstrings' to potentially inject additional fields into marshalled documents. This is a data integrity issue where untrusted input can bypass validation during the Go-to-BSON conversion.
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
Go DriverApplication
<= 1.5.0CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
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 MongoDB Go Driver usageSearch your codebase for imports of the MongoDB Go Driver (e.g., 'go.mongodb.org/mongo-driver/mongo' or 'go.mongodb.org/mongo-driver/bson') and check your go.mod file for the driver dependency.Affected if The driver is present in your project dependencies.
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Determine installed driver versionRun 'go list -m all' or check your go.mod file for the 'go.mongodb.org/mongo-driver' version entry. Compare this version number to the affected range (all versions <= 1.5.0).Affected if The installed version is 1.5.0 or any lower version number.
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Locate BSON marshalling operationsSearch your codebase for calls to bson.Marshal, bson.MarshalJSON, or struct tags with bson: directives that perform marshalling of Go structs to BSON documents.Affected if Your application performs Go-to-BSON conversion on any data structures.
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Identify untrusted input handlingReview code paths where external input (user data, API payloads, file contents, network requests) flows into BSON marshalling functions. Check for patterns where data from HTTP requests, JSON APIs, or external files is directly passed to bson.Marshal().Affected if Untrusted or user-controlled data is passed to BSON marshalling functions without prior validation.
You are affected if your project uses the MongoDB Go Driver at version 1.5.0 or lower and processes external input through BSON marshalling operations.
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.
From vendor dataUpgrade the MongoDB Go Driver to a version newer than 1.5.0 to receive the patch for proper cstring validation during BSON marshalling.
Fix this in Go Driver
Scoped from the published advisory
- Consultation2.0 h
- Implementation1.0 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 $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20329 — 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-2021-20329 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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- Version or environment caveats, and links to real fixes
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