How severe is CVE-2020-15955?

CVE-2020-15955 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2020-15955 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-15955?

CVE-2020-15955 affects Fehcom S/qmail. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-15955?

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

When was CVE-2020-15955 published?

CVE-2020-15955 was published on 2021-08-17 and last updated on 2026-06-17.

CVE-2020-15955

CVE-2020-15955 is a medium-severity vulnerability in Fehcom S/qmail with a CVSS 3.x base score of 5.9. 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-77.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 4.3
EPSS exploit prediction: 1% (57th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-77
Affected product: Fehcom S/qmail
Published: 2021-08-17
Last modified: 2026-06-17

Description

In s/qmail through 4.0.07, an active MitM can inject arbitrary plaintext commands into a STARTTLS encrypted session between an SMTP client and s/qmail. This allows e-mail messages and user credentials to be sent to the MitM attacker.

Frequently asked questions

What is CVE-2020-15955?: In s/qmail through 4.0.07, an active MitM can inject arbitrary plaintext commands into a STARTTLS encrypted session between an SMTP client and s/qmail. This allows e-mail messages and user credentials to be sent to the MitM attacker.
How severe is CVE-2020-15955?: CVE-2020-15955 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2020-15955 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (57th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-15955?: CVE-2020-15955 affects Fehcom S/qmail. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-15955?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-15955 published?: CVE-2020-15955 was published on 2021-08-17 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:fehcom:s\/qmail:*:*:*:*:*:*:*:*

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