CVE-2020-7616: express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution

Q: How do I fix CVE-2020-7616?

express-mock-middleware: upgrade to newer than 0.0.6. Exact commands for each OS are on this page.

Q: Is CVE-2020-7616 being exploited?

CVE-2020-7616 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-7616 affect?

CVE-2020-7616 affects express-mock-middleware. Severity is medium (CVSS 5.3). express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation

Q: How urgent is CVE-2020-7616?

Priority 46/100. Public exploit reference; Remotely exploitable, no login, no user action

This week

MEDIUM 5.3REMOTEUPGRADE

CVE-2020-7616 is a medium-severity flaw (CVSS 5.3) affecting express-mock-middleware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation of a new directory where an attack code can be placed which will then be exported by `express-mock-middleware`. As such, this is considered to be a low risk.

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.3% (top 30%)
CISA exploited list	No
Weakness	CWE-1321
Published	2020-04-07
Last modified	2026-06-17

Publisher (CNA): Snyk · Vendor: express-mock-middleware project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-04-07 14:15 UTCPublished CVE record published
2026-06-17 03:25 UTCUpdated Record last modified

express-mock-middleware project express-mock-middleware UPGRADE

Affected: <= 0.0.6

Fixed in: newer than 0.0.6

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy express-mock-middleware || rpm -q express-mock-middleware || express-mock-middleware --version

2. UPGRADE to newer than 0.0.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade express-mock-middleware

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade express-mock-middleware

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-7616?

express-mock-middleware: upgrade to newer than 0.0.6. Exact commands for each OS are on this page.

Is CVE-2020-7616 being exploited?

CVE-2020-7616 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-7616 affect?

CVE-2020-7616 affects express-mock-middleware. Severity is medium (CVSS 5.3). express-mock-middleware through 0.0.6 is vulnerable to Prototype Pollution. Exported functions by the package can be tricked into adding or modifying properties of the `Object.prototype`. Exploitation of this vulnerability requires creation

How urgent is CVE-2020-7616?

Priority 46/100. Public exploit reference; Remotely exploitable, no login, no user action

References

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