How severe is CVE-2020-8156?

CVE-2020-8156 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability low.

Is CVE-2020-8156 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-8156?

CVE-2020-8156 primarily affects Nextcloud Mail. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-8156?

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-2020-8156 published?

CVE-2020-8156 was published on 2020-05-12 and last updated on 2026-06-17.

CVE-2020-8156

CVE-2020-8156 is a high-severity vulnerability in Nextcloud Mail with a CVSS 3.x base score of 7.0. 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-295.

Key facts

Severity: High (CVSS 3.x base score 7.0)
CVSS v2: 6.8
EPSS exploit prediction: 1% (56th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Nextcloud Mail
Published: 2020-05-12
Last modified: 2026-06-17

Description

A missing verification of the TLS host in Nextcloud Mail 1.1.3 allowed a man in the middle attack.

Frequently asked questions

What is CVE-2020-8156?: A missing verification of the TLS host in Nextcloud Mail 1.1.3 allowed a man in the middle attack.
How severe is CVE-2020-8156?: CVE-2020-8156 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability low.
Is CVE-2020-8156 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (56th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-8156?: CVE-2020-8156 primarily affects Nextcloud Mail. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-8156?: 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-2020-8156 published?: CVE-2020-8156 was published on 2020-05-12 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:nextcloud:mail:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*

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