CVE-2021-37862Network attack vector

Account misattribution via unvalidated invitation email

Published Dec 17, 2021 · Updated Aug 4, 2024

Improper email validation in Mattermost 6.0 and earlier allows remote authenticated users to misattribute new accounts via crafted invitation tokens. The registration path accepts the email address carried by an invitation token without sufficiently validating it before creating the account. An authenticated attacker must persuade a user to complete registration, and the resulting account is tied to an email address controlled by the attacker.

CVSS severity3.7
Low
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper email validation in Mattermost 6.0 and earlier allows remote authenticated users to misattribute new accounts via crafted invitation tokens. The registration path accepts the email address carried by an invitation token without sufficiently validating it before creating the account. An authenticated attacker must persuade a user to complete registration, and the resulting account is tied to an email address controlled by the attacker.

The record

CVE
CVE-2021-37862
Published
Dec 17, 2021
Updated
Aug 4, 2024
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-754, T1566.002
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <=6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=unspecified <=6.0

Published CVSS scores

3.7Mattermost, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N
5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-754Improper Check for Unusual or Exceptional Conditions
T1566.002Spearphishing Link

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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