CVE-2016-11066: Mattermost Server Initial_load API Exposes Unnecessary Information Vulnerability

HIGH
Advisory Identifier: GHSA-r93j-3mmp-px57
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CVSS 7.5
CWE-200 CWE-359
Published
Advisory Summary

CVE-2016-11066 is a HIGH (CVSS 7.5) initial_load api exposes unnecessary information vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting Mattermost Server libraries in the Go ecosystem. The issue involves initial_load api exposes unnecessary information. Remediation is available by upgrading affected packages to version 3.1.1.

CVE-2016-11066 at a Glance

CVE Identifier CVE-2016-11066
GHSA Identifier GHSA-r93j-3mmp-px57
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product Mattermost Server
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.5

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

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

How to Fix CVE-2016-11066

To remediate this vulnerability, upgrade all affected 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: 3.1.1 
Upgrade github.com/mattermost/mattermost-server to 3.1.1
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-2016-11066, inspect your project dependencies for Mattermost Server:

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

Analyze the terminal output to locate any version of Mattermost Server in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.1.1), 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-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In 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 3.1.1. The initial_load API disclosed unnecessary personal information.

CVE-2016-11066 Affected Mattermost Server Versions

1 component(s)
Fixed Versions:
3.1.1
Product / Package Ecosystem Affected Versions Fixed Version
github.com/mattermost/mattermost-server
golang/github.com/mattermost/mattermost-server
Go
< 3.1.1
3.1.1

References

NVD — CVE-2016-11066 NVD
https://nvd.nist.gov/vuln/detail/CVE-2016-11066
Security Fix Commit FIX COMMIT
https://github.com/mattermost/mattermost/commit/f89e7c6d543a82d6078c2ca0f892914d7976a6f5
Mattermost Server Source Repository REPOSITORY
https://github.com/mattermost/mattermost
Mattermost Server Security Information SECURITY
https://mattermost.com/security-updates

Frequently Asked Questions

What is CVE-2016-11066?
CVE-2016-11066 is a security vulnerability in Mattermost Server involving initial_load API exposes unnecessary information under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which Mattermost Server versions are affected?
Affected versions include releases prior to 3.1.1 across affected packages: github.com/mattermost/mattermost-server.
What version fixes CVE-2016-11066?
Upgrading to 3.1.1 (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 3.1.1. Upgrade your dependency to 3.1.1 or later.
What is the CVSS score of CVE-2016-11066?
CVE-2016-11066 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2016-11066?
CVE-2016-11066 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check Go dependencies for CVE-2016-11066?
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-r93j-3mmp-px57",
  "modified" : "2025-10-21T22:38:56Z",
  "published" : "2022-05-24T17:21:01Z",
  "aliases" : [ "CVE-2016-11066" ],
  "summary" : "Mattermost Server: initial_load API exposes unnecessary information",
  "details" : "An issue was discovered in Mattermost Server before 3.1.1. The initial_load API disclosed unnecessary personal information.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/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" : "3.1.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2016-11066"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/mattermost/mattermost/commit/f89e7c6d543a82d6078c2ca0f892914d7976a6f5"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/mattermost/mattermost"
  }, {
    "type" : "WEB",
    "url" : "https://mattermost.com/security-updates"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-359" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-10-21T22:38:28Z",
    "nvd_published_at" : "2020-06-19T20:15:00Z"
  }
}