CVE-2025-8402: Github.com/mattermost/mattermost server Mattermost Has Potential Server Crash Vulnerability

MODERATE
Advisory Identifier: GHSA-h469-4fcf-p23h
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CVSS 4.9
CWE-476
Published
Advisory Summary

CVE-2025-8402 is a MODERATE (CVSS 4.9) mattermost has potential server crash vulnerability (CWE-476: NULL Pointer Dereference) affecting Github.com/mattermost/mattermost server libraries in the Go ecosystem. The issue involves mattermost has potential server crash due to unvalidated import data. Remediation is available by upgrading affected packages to version 10.8.4, 10.5.9, 10.9.4, 10.10.1, 8.0.0-20250708173752-d6b35c41f0ae5, 9.11.18.

CVE-2025-8402 at a Glance

CVE Identifier CVE-2025-8402
GHSA Identifier GHSA-h469-4fcf-p23h
Severity MODERATE
CVSS v3.1 Base Score 4.9
CWE Classification CWE-476: NULL Pointer Dereference
Affected Product Github.com/mattermost/mattermost server
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 4.9

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required High (PR:H)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2025-8402

To remediate this vulnerability, upgrade all affected Github.com/mattermost/mattermost server dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/mattermost/mattermost-server fixed: 10.8.4 
Upgrade github.com/mattermost/mattermost-server to 10.8.4
github.com/mattermost/mattermost-server fixed: 10.5.9 
Upgrade github.com/mattermost/mattermost-server to 10.5.9
github.com/mattermost/mattermost-server fixed: 10.9.4 
Upgrade github.com/mattermost/mattermost-server to 10.9.4
github.com/mattermost/mattermost-server fixed: 10.10.1 
Upgrade github.com/mattermost/mattermost-server to 10.10.1
github.com/mattermost/mattermost/server/v8 fixed: 8.0.0-20250708173752-d6b35c41f0ae5 
Upgrade github.com/mattermost/mattermost/server/v8 to 8.0.0-20250708173752-d6b35c41f0ae5
github.com/mattermost/mattermost-server fixed: 9.11.18 
Upgrade github.com/mattermost/mattermost-server to 9.11.18
github.com/mattermost/mattermost-server/v5 fixed: Latest secure release 
Upgrade github.com/mattermost/mattermost-server/v5 to Latest secure release
github.com/mattermost/mattermost-server/v6 fixed: Latest secure release 
Upgrade github.com/mattermost/mattermost-server/v6 to Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/mattermost/mattermost-server

How to Check if You Are Affected

To determine whether your application is affected by CVE-2025-8402, inspect your project dependencies for Github.com/mattermost/mattermost server:

inspect dependencies for github.com/mattermost/mattermost-server

Analyze the terminal output to locate any version of Github.com/mattermost/mattermost server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 10.8.4), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-476: NULL Pointer Dereference, where the product dereferences a pointer that it expects to be valid but is null. In Github.com/mattermost/mattermost server, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature.

CVE-2025-8402 Affected Github.com/mattermost/mattermost server Versions

8 component(s)
Fixed Versions:
10.8.410.5.910.9.410.10.18.0.0-20250708173752-d6b35c41f0ae59.11.18
Product / Package Ecosystem Affected Versions Fixed Version
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 10.8.0
< 10.8.4
10.8.4
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 10.5.0
< 10.5.9
10.5.9
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 10.9.0
< 10.9.4
10.9.4
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 10.10.0
< 10.10.1
All 1 versions
10.10.0
10.10.1
github.com/mattermost/mattermost/server/v8
golang/github.com/mattermost/mattermost/server/v8
Go
< 8.0.0-20250708173752-d6b35c41f0ae5
8.0.0-20250708173752-d6b35c41f0ae5
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 9.11.0
< 9.11.18
9.11.18
github.com/mattermost/mattermost-server/v5
golang/github.com/mattermost/mattermost-server/v5
Go
≤ 5.39.3
github.com/mattermost/mattermost-server/v6
golang/github.com/mattermost/mattermost-server/v6
Go
≤ 6.7.2

References

NVD — CVE-2025-8402 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-8402
Github.com/mattermost/mattermost server Source Repository REPOSITORY
https://github.com/mattermost/mattermost
Github.com/mattermost/mattermost server Security Information SECURITY
https://mattermost.com/security-updates
pkg.go.dev/vuln/go-2025-3911 WEB
https://pkg.go.dev/vuln/GO-2025-3911

Frequently Asked Questions

What is CVE-2025-8402?
CVE-2025-8402 is a security vulnerability in Github.com/mattermost/mattermost server involving Mattermost has Potential Server Crash due to Unvalidated Import Data under CWE-476: NULL Pointer Dereference.
Which Github.com/mattermost/mattermost server versions are affected?
Affected versions include releases prior to 10.8.4, 10.5.9, 10.9.4, 10.10.1, 8.0.0-20250708173752-d6b35c41f0ae5, 9.11.18 across affected packages: github.com/mattermost/mattermost-server, github.com/mattermost/mattermost/server/v8, github.com/mattermost/mattermost-server/v5, github.com/mattermost/mattermost-server/v6.
What version fixes CVE-2025-8402?
Upgrading to 10.8.4, 10.5.9, 10.9.4, 10.10.1, 8.0.0-20250708173752-d6b35c41f0ae5, 9.11.18 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/mattermost/mattermost-server affected?
Yes, github.com/mattermost/mattermost-server is affected in releases prior to 10.8.4, 10.5.9, 10.9.4, 10.10.1, 9.11.18. Upgrade your dependency to 10.8.4, 10.5.9, 10.9.4, 10.10.1, 9.11.18 or later.
Is github.com/mattermost/mattermost/server/v8 affected?
Yes, github.com/mattermost/mattermost/server/v8 is affected in releases prior to 8.0.0-20250708173752-d6b35c41f0ae5. Upgrade your dependency to 8.0.0-20250708173752-d6b35c41f0ae5 or later.
What is the CVSS score of CVE-2025-8402?
CVE-2025-8402 has a CVSS v3.1 base score of 4.9 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2025-8402?
CVE-2025-8402 is classified under CWE-476: NULL Pointer Dereference (The product dereferences a pointer that it expects to be valid but is NULL.).
How can I check Go dependencies for CVE-2025-8402?
Run the dependency tree command: 'inspect dependencies for github.com/mattermost/mattermost-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-h469-4fcf-p23h",
  "modified" : "2025-08-29T21:02:12Z",
  "published" : "2025-08-21T18:31:29Z",
  "aliases" : [ "CVE-2025-8402" ],
  "summary" : "Mattermost has Potential Server Crash due to Unvalidated Import Data",
  "details" : "Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.0, 10.9.x <= 10.9.3 fail to validate import data which allows a system admin to crash the server via the bulk import feature.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.8.0"
      }, {
        "fixed" : "10.8.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.8.3"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.5.0"
      }, {
        "fixed" : "10.5.9"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.5.8"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.9.0"
      }, {
        "fixed" : "10.9.4"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 10.9.3"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "10.10.0"
      }, {
        "fixed" : "10.10.1"
      } ]
    } ],
    "versions" : [ "10.10.0" ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost/server/v8"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.0.0-20250708173752-d6b35c41f0ae5"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "9.11.0"
      }, {
        "fixed" : "9.11.18"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 9.11.17"
    }
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server/v5"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "5.39.3"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server/v6"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "6.7.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-8402"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost"
  }, {
    "type" : "WEB",
    "url" : "https://mattermost.com/security-updates"
  }, {
    "type" : "WEB",
    "url" : "https://pkg.go.dev/vuln/GO-2025-3911"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-476" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-08-22T17:34:35Z",
    "nvd_published_at" : "2025-08-21T17:15:33Z"
  }
}