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CVE-2026-24458 — Vulnerability in...

HIGH

Mattermost fails to properly handle very long passwords

Published March 16, 2026Updated March 23, 2026Source: osv

Summary

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to properly handle very long passwords, which allows an attacker to overload the server CPU and memory via executing login attempts with multi-megabyte passwords. Mattermost Advisory ID: MMSA-2026-00587

Advisory Timeline

  • First published March 16, 2026 (210 days ago).
  • Last revised March 23, 2026 — 7 days after initial publication.

Remediation

Upgrade to the fixed version using your package manager.

Go
Update github.com/mattermost/mattermost/server/v8 to 8.0.0-20260129164748-7201f42d955f or later
go get github.com/mattermost/mattermost/server/v8@v8.0.0-20260129164748-7201f42d955f
Go
Update github.com/mattermost/mattermost-server to 5.3.2-0.20260129164748-7201f42d955f or later
go get github.com/mattermost/mattermost-server@v5.3.2-0.20260129164748-7201f42d955f
Go
Update github.com/mattermost/mattermost-server to 11.3.1 or later
go get github.com/mattermost/mattermost-server@v11.3.1
Go
Update github.com/mattermost/mattermost-server to 10.11.11 or later
go get github.com/mattermost/mattermost-server@v10.11.11
Go
Update github.com/mattermost/mattermost-server to 11.2.3 or later
go get github.com/mattermost/mattermost-server@v11.2.3

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (5)

Affects 1 ecosystem: go (2).

PackageEcosystemAffectedFixed In
github.com/mattermost/mattermost/server/v8
go
All versions8.0.0-20260129164748-7201f42d955f
github.com/mattermost/mattermost-server
go
All versions5.3.2-0.20260129164748-7201f42d955f
github.com/mattermost/mattermost-server
go
All versions11.3.1
github.com/mattermost/mattermost-server
go
All versions10.11.11
github.com/mattermost/mattermost-server
go
All versions11.2.3

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

  • CWE-770
    Allocation of Resources Without LimitsMITRE

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 7.5 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Frequently Asked Questions

What is CVE-2026-24458?
Mattermost fails to properly handle very long passwords This vulnerability has been assigned a severity rating of HIGH (CVSS score: 7.5/10).
How do I check if my project is affected by CVE-2026-24458?
CVE-2026-24458 affects github.com/mattermost/mattermost/server/v8 and github.com/mattermost/mattermost-server. Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2026-24458 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
7.5

High exploitability or significant impact. Prioritize remediation within days.

Also Known As

GHSA-m5rv-56xx-hfc6
GO-2026-4731

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  • CVE-2025-58073
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  • CVE-2025-9079
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