How severe is CVE-2021-21304?

CVE-2021-21304 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-21304?

CVE-2021-21304 affects the following packages: dynamoose (npm). Ecosystems affected: npm.

How do I fix CVE-2021-21304?

Update dynamoose to 2.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21304 is resolved across your whole dependency graph.

How do I detect CVE-2021-21304 in my npm dependencies?

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

How do I mitigate CVE-2021-21304 if there is no patch (or I can't update yet)?

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.

Is CVE-2021-21304 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-21304 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-21304?

CVE-2021-21304 has an EPSS (Exploit Prediction Scoring System) score of 1.9%, placing it in the 79th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-21304?

CVE-2021-21304 is classified as CWE-915 (CWE-915), CWE-1321 (CWE-1321). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-21304 published, and has it been updated?

CVE-2021-21304 was published on February 8, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

CRITICAL severity

CVE-2021-21304 — dynamoose

CRITICALFix: dynamoose/dynamoose@324c62b

CVE-2021-21304 is a critical-severity (CVSS 9.8) CWE-915 vulnerability in dynamoose. A fix is available for dynamoose — see the affected versions and patch details below.

Prototype Pollution in Dynamoose

Also known asGHSA-rrqm-p222-8ph2

Published

Feb 8, 2021

Updated

Jul 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.9%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs79th percentile — riskier than 79% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-21304 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

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.

214other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

dynamoosenpm

242Kdownloads / week

Description

Impact

In Dynamoose versions 2.0.0-2.6.0 there was a prototype pollution vulnerability in the internal utility method lib/utils/object/set.ts. This method is used throughout the codebase for various operations throughout Dynamoose.

We have not seen any evidence of this vulnerability being exploited.

We do not believe this issue impacts v1.x.x since this method was added as part of the v2 rewrite. This vulnerability also impacts v2.x.x beta/alpha versions.

Patches

v2.7.0 includes a patch for this vulnerability.

Workarounds

We are unaware of any workarounds to patch this vulnerability other than upgrading to v2.7.0 or greater.

References

Patch commit hash: 324c62b4709204955931a187362f8999805b1d8e

For more information

If you have any questions or comments about this advisory:

Credit

GitHub CodeQL Code Scanning

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`dynamoose`	≥ 2.0.0&&< 2.7.0	2.7.0`npm install dynamoose@2.7.0`

Affected Products

1 product · 1 configurations

Application

dynamoosedynamoosejs

≥ 2.0.0 && < 2.7.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dynamoose, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update dynamoose to 2.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-21304 is resolved across your whole dependency graph.
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.

Frequently Asked Questions

### Impact In Dynamoose versions 2.0.0-2.6.0 there was a prototype pollution vulnerability in the internal utility method [`lib/utils/object/set.ts`](https://github.com/dynamoose/dynamoose/blob/master/lib/utils/object/set.ts). This method is used throughout the codebase for various operations throughout Dynamoose. We have not seen any evidence of this vulnerability being exploited. We do not believe this issue impacts v1.x.x since this method was added as part of the v2 rewrite. This vulnerability also impacts v2.x.x beta/alpha versions. ### Patches v2.7.0 includes a patch for this vulner