How severe is CVE-2021-37862?

CVE-2021-37862 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-37862 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-37862?

CVE-2021-37862 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-37862?

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

When was CVE-2021-37862 published?

CVE-2021-37862 was published on 2021-12-17 and last updated on 2026-06-17.

CVE-2021-37862

CVE-2021-37862 is a low-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 3.7. 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-754.

Key facts

Severity: Low (CVSS 3.x base score 3.7)
CVSS v2: 5.8
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-754
Affected product: Mattermost Mattermost Server
Published: 2021-12-17
Last modified: 2026-06-17

Description

Mattermost 6.0 and earlier fails to sufficiently validate the email address during registration, which allows attackers to trick users into signing up using attacker-controlled email addresses via crafted invitation token.

Frequently asked questions

What is CVE-2021-37862?: Mattermost 6.0 and earlier fails to sufficiently validate the email address during registration, which allows attackers to trick users into signing up using attacker-controlled email addresses via crafted invitation token.
How severe is CVE-2021-37862?: CVE-2021-37862 has a CVSS 3.x base score of 3.7, rated low severity. It is exploitable over network with high attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-37862 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-37862?: CVE-2021-37862 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-37862?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-37862 published?: CVE-2021-37862 was published on 2021-12-17 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

More vulnerabilities in Mattermost Mattermost Server

CVE-2025-12421 — Critical (CVSS 9.9): Mattermost versions 11.0.x <= 11.0.2, 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12 fail to to verify that…
CVE-2025-12419 — Critical (CVSS 9.9): Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly…
CVE-2025-4981 — Critical (CVSS 9.9): Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to…
CVE-2025-25279 — Critical (CVSS 9.9): Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate…
CVE-2025-20051 — Critical (CVSS 9.9): Mattermost versions 10.4.x <= 10.4.1, 9.11.x <= 9.11.7, 10.3.x <= 10.3.2, 10.2.x <= 10.2.2 fail to properly validate…
CVE-2017-18920 — Critical (CVSS 9.8): An issue was discovered in Mattermost Server before 3.6.2. The WebSocket feature does not follow the Same Origin Policy.

All CVEs affecting Mattermost Mattermost Server →

Other CWE-754 (Improper Check for Unusual or Exceptional Conditions) vulnerabilities

CVE-2026-24054 — Critical (CVSS 10.0): Kata Containers is an open source project focusing on a standard implementation of lightweight Virtual Machines (VMs)…
CVE-2021-0211 — Critical (CVSS 10.0): An improper check for unusual or exceptional conditions in Juniper Networks Junos OS and Junos OS Evolved Routing…
CVE-2026-8091 — Critical (CVSS 9.8): Incorrect boundary conditions in the Audio/Video: Playback component. This vulnerability was fixed in Firefox 150,…
CVE-2024-52316 — Critical (CVSS 9.8): Unchecked Error Condition vulnerability in Apache Tomcat. If Tomcat is configured to use a custom Jakarta…
CVE-2024-7826 — Critical (CVSS 9.8): Improper Check for Unusual or Exceptional Conditions vulnerability in Webroot SecureAnywhere - Web Shield on Windows,…
CVE-2023-37303 — Critical (CVSS 9.8): An issue was discovered in the CheckUser extension for MediaWiki through 1.39.3. In certain situations, an attempt to…

Browse all CWE-754 (Improper Check for Unusual or Exceptional Conditions) vulnerabilities →