How severe is CVE-2019-2391?

CVE-2019-2391 has a CVSS score of 5.4/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2019-2391?

CVE-2019-2391 affects the following packages: bson (npm). Ecosystems affected: npm.

How do I fix CVE-2019-2391?

Update bson to 1.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-2391 is resolved across your whole dependency graph.

How do I detect CVE-2019-2391 in my npm dependencies?

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

How do I mitigate CVE-2019-2391 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2019-2391 actively exploited in the wild?

No public exploit code has been indexed for CVE-2019-2391 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-2019-2391?

CVE-2019-2391 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 54th 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-2019-2391?

CVE-2019-2391 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2019-2391 published, and has it been updated?

CVE-2019-2391 was published on March 31, 2020 and was last updated on July 8, 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

MEDIUM severity

CVE-2019-2391 — bson

MEDIUM

CVE-2019-2391 is a medium-severity (CVSS 5.4) Deserialization of Untrusted Data vulnerability in bson. A fix is available for bson — see the affected versions and patch details below.

Deserialization of Untrusted Data in bson

Also known asGHSA-4jwp-vfvf-657p

Published

Mar 31, 2020

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk-0.12%

Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2019-2391 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 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.

2Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

bsonnpm

19.1Mdownloads / week

Description

Incorrect parsing of certain JSON input may result in js-bson not correctly serializing BSON. This may cause unexpected application behaviour including data disclosure. This issue affects: MongoDB Inc. js-bson library version 1.1.3 and prior to.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`bson`	all versions	1.1.4`npm install bson@1.1.4`

Affected Products

1 product · 1 configurations

Application

js-bsonmongodb

< 1.1.4

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for bson, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update bson to 1.1.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-2391 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2019-2391 in your dependencies?

Find it across npm, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

5.4/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CWE Classification

CWE-502Deserialization of Untrusted Data

Weaponization

No known public exploit tooling found.

OpenSSF Scorecard

Package health score

js-bson

6.3/10

Maintained10/10

Code-Review10/10

Branch-Protection5/10

Assessed Oct 5, 2026

Timeline

Disclosed

Mar 31, 2020

Last updated

Jul 8, 2026

Identifiers

CVE-2019-2391

GHSA-4jwp-vfvf-657p

References

Advisorynvd.nist.gov Fixgithub.com Packagegithub.com

Related vulnerabilities

Also affects bson

This CVE is medium severity; 2 of 2 other CVEs affecting bson are rated as high or higher (top: critical).

CVE-2020-7610CVE-2018-13863

Same weakness: CWE-502

This CVE is medium severity; 5 of 6 other CVEs with CWE-502 are rated as high or higher (top: critical).

CVE-2025-66455CVE-2025-59953CVE-2026-49400CVE-2026-50646CVE-2026-78683CVE-2026-79657Browse all CWE-502

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJul 8, 2026