How severe is CVE-2021-23400?

CVE-2021-23400 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2021-23400 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-23400?

CVE-2021-23400 affects Nodemailer. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-23400?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-23400 published?

CVE-2021-23400 was published on 2021-06-29 and last updated on 2026-06-17.

CVE-2021-23400

CVE-2021-23400 is a medium-severity vulnerability in Nodemailer with a CVSS 3.x base score of 6.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-74.

Key facts

Severity: Medium (CVSS 3.x base score 6.3)
CVSS v2: 6.8
EPSS exploit prediction: 1% (69th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-74
Affected product: Nodemailer
Published: 2021-06-29
Last modified: 2026-06-17

Description

The package nodemailer before 6.6.1 are vulnerable to HTTP Header Injection if unsanitized user input that may contain newlines and carriage returns is passed into an address object.

Frequently asked questions

What is CVE-2021-23400?: The package nodemailer before 6.6.1 are vulnerable to HTTP Header Injection if unsanitized user input that may contain newlines and carriage returns is passed into an address object.
How severe is CVE-2021-23400?: CVE-2021-23400 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2021-23400 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (69th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-23400?: CVE-2021-23400 affects Nodemailer. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-23400?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-23400 published?: CVE-2021-23400 was published on 2021-06-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nodemailer:nodemailer:*:*:*:*:*:node.js:*:*

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