How severe is CVE-2021-38371?

CVE-2021-38371 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-38371 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-38371?

CVE-2021-38371 affects Exim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-38371?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-38371 published?

CVE-2021-38371 was published on 2021-08-10 and last updated on 2026-06-17.

CVE-2021-38371

CVE-2021-38371 is a high-severity vulnerability in Exim with a CVSS 3.x base score of 7.5. 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: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (78th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-74
Affected product: Exim
Published: 2021-08-10
Last modified: 2026-06-17

Description

The STARTTLS feature in Exim through 4.94.2 allows response injection (buffering) during MTA SMTP sending.

Frequently asked questions

What is CVE-2021-38371?: The STARTTLS feature in Exim through 4.94.2 allows response injection (buffering) during MTA SMTP sending.
How severe is CVE-2021-38371?: CVE-2021-38371 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-38371 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (78th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-38371?: CVE-2021-38371 affects Exim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-38371?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-38371 published?: CVE-2021-38371 was published on 2021-08-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

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Threat intelligence

Threat-intel indicators referencing this CVE:

76.12.128.249 (ipv4-addr)
50.116.72.139 (ipv4-addr)
166.62.41.190 (ipv4-addr)
132.148.155.138 (ipv4-addr)
37.221.254.200 (ipv4-addr)
50.62.22.47 (ipv4-addr)
31.131.22.122 (ipv4-addr)
193.68.57.43 (ipv4-addr)