CVE-2017-18883: Github.com/mattermost/mattermost server Mattermost Server Has Low Entropy Vulnerability

MODERATE
Advisory Identifier: GHSA-w8cc-3h7q-jhc3
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CWE-331
Published
Advisory Summary

CVE-2017-18883 is a MODERATE mattermost server has low entropy vulnerability (CWE-331: Insufficient Entropy) affecting Github.com/mattermost/mattermost server libraries in the Go ecosystem. The issue involves mattermost server has low entropy for authorization data as an oauth 2.0 service provider. Remediation is available by upgrading affected packages to version 4.1.2, 4.2.1, 4.3.0.

CVE-2017-18883 at a Glance

CVE Identifier CVE-2017-18883
GHSA Identifier GHSA-w8cc-3h7q-jhc3
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-331: Insufficient Entropy
Affected Product Github.com/mattermost/mattermost server
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2017-18883

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: 4.1.2 
Upgrade github.com/mattermost/mattermost-server to 4.1.2
github.com/mattermost/mattermost-server fixed: 4.2.1 
Upgrade github.com/mattermost/mattermost-server to 4.2.1
github.com/mattermost/mattermost-server fixed: 4.3.0 
Upgrade github.com/mattermost/mattermost-server to 4.3.0
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-2017-18883, 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 4.1.2), 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-331: Insufficient Entropy, where the product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others. 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

An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2, when serving as an OAuth 2.0 Service Provider. There is low entropy for authorization data.

CVE-2017-18883 Affected Github.com/mattermost/mattermost server Versions

3 component(s)
Fixed Versions:
4.1.24.2.14.3.0
Product / Package Ecosystem Affected Versions Fixed Version
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
< 4.1.2
4.1.2
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 4.2.0-rc1
< 4.2.1
4.2.1
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
≥ 4.3.0-rc1
< 4.3.0
4.3.0

References

NVD — CVE-2017-18883 NVD
https://nvd.nist.gov/vuln/detail/CVE-2017-18883
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

Frequently Asked Questions

What is CVE-2017-18883?
CVE-2017-18883 is a security vulnerability in Github.com/mattermost/mattermost server involving Mattermost Server has low entropy for authorization data as an OAuth 2.0 Service Provider under CWE-331: Insufficient Entropy.
Which Github.com/mattermost/mattermost server versions are affected?
Affected versions include releases prior to 4.1.2, 4.2.1, 4.3.0 across affected packages: github.com/mattermost/mattermost-server.
What version fixes CVE-2017-18883?
Upgrading to 4.1.2, 4.2.1, 4.3.0 (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 4.1.2, 4.2.1, 4.3.0. Upgrade your dependency to 4.1.2, 4.2.1, 4.3.0 or later.
What CWE is associated with CVE-2017-18883?
CVE-2017-18883 is classified under CWE-331: Insufficient Entropy (The product uses an algorithm or scheme that produces insufficient entropy, leaving patterns or clusters of values that are more likely to occur than others.).
How can I check Go dependencies for CVE-2017-18883?
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-w8cc-3h7q-jhc3",
  "modified" : "2025-12-05T19:37:33Z",
  "published" : "2022-05-24T17:21:03Z",
  "aliases" : [ "CVE-2017-18883" ],
  "summary" : "Mattermost Server has low entropy for authorization data as an OAuth 2.0 Service Provider",
  "details" : "An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2, when serving as an OAuth 2.0 Service Provider. There is low entropy for authorization data.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.1.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.2.0-rc1"
      }, {
        "fixed" : "4.2.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/mattermost/mattermost-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.3.0-rc1"
      }, {
        "fixed" : "4.3.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2017-18883"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost"
  }, {
    "type" : "WEB",
    "url" : "https://mattermost.com/security-updates"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-331" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-12-05T19:37:33Z",
    "nvd_published_at" : "2020-06-19T19:15:00Z"
  }
}