CVE-2024-39836Network attack vector

Remote-user account takeover via munged email addresses

Published Aug 22, 2024 · Updated Aug 22, 2024

Protection mechanism failure in affected Mattermost 9.x releases allows remote attackers to reset remote-user passwords. Shared Channels generate remote or synthetic users with munged email addresses, but session and password-reset checks fail to exclude those accounts when a munged address is a functional mailbox. A reachable functional mailbox for the generated address is required, and control of it enables email receipt, password reset, and creation of an authenticated session.

CVSS severity4.8
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protection mechanism failure in affected Mattermost 9.x releases allows remote attackers to reset remote-user passwords. Shared Channels generate remote or synthetic users with munged email addresses, but session and password-reset checks fail to exclude those accounts when a munged address is a functional mailbox. A reachable functional mailbox for the generated address is required, and control of it enables email receipt, password reset, and creation of an authenticated session.

The record

CVE
CVE-2024-39836
Published
Aug 22, 2024
Updated
Aug 22, 2024
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-693, T1078
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 22, 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=9.10.0
  2. Affected versionversion=9.5.0 <=9.5.7
  3. Affected versionversion=9.8.0 <=9.8.2
  4. Affected versionversion=9.9.0 <=9.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mattermost · Mattermostversion=9.10.0; version=9.5.0 <=9.5.7; version=9.8.0 <=9.8.2; version=9.9.0 <=9.9.1

Published CVSS scores

4.8Mattermost, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-693Protection Mechanism Failure
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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