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MybbApplication

CVE-2015-2786

HIGH · 10.0 CVSS v2.0 Published 2015-03-29
Fix available
A fix is available. Upgrade to after 1.8.3 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Unspecified vulnerability in MyBB (aka MyBulletinBoard) before 1.8.4 has unknown attack vectors related to "Group join request notifications sent to wrong group leaders."

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

MyBB before version 1.8.4 contains a vulnerability in its group management system where join requests for user groups are incorrectly routed to the wrong group leaders. This is a confidentiality and access control issue where sensitive membership request notifications are delivered to unauthorized users instead of the intended group administrators.

MitigationUpgrade MyBB to version 1.8.4 or later. If unable to upgrade, review the group leader notification code paths in the software and implement access control checks to ensure join requests are only sent to the correct group leaders.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
MybbApplication
Affected:<= 1.8.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Authentication
None
Confidentiality
Complete
Integrity
Complete
Availability
Complete

AV:N/AC:L/Au:N/C:C/I:C/A:C

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed MyBB version
    Access the MyBB admin control panel and navigate to Home > Board Statistics, or inspect the inc/class_core.php file for the $mybb->version variable. Alternatively, check the version number displayed in the footer of the forum pages.
    Affected if The installed version is 1.8.3 or earlier (any version <= 1.8.3)
  2. Verify group management feature is in use
    Log into the MyBB admin panel and navigate to Users & Groups > Groups. Confirm that there are user groups configured on the forum.
    Affected if User groups exist and the group leader functionality is configured
  3. Identify group leader configuration
    In the admin panel under Users & Groups > Groups, examine each group's settings to determine which groups have assigned leaders. Click on a group and look for the Leader(s) field.
    Affected if Multiple group leaders are assigned to different groups, creating the condition where requests could be routed to the wrong leader
  4. Review group join request handling
    Submit a test group join request (or review existing request logs) and observe which group leader receives the notification. This requires checking the group_leaders table in the database or monitoring PM/notification deliveries.
    Affected if Join requests for a specific group are delivered to a leader other than the intended group administrator

Your environment is affected if MyBB version is 1.8.3 or earlier AND group leader functionality is configured, as the incorrect routing of group join requests to unauthorized leaders requires both conditions to be present.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 1.8.3
Vendor patch blog.mybb.com →
Interim mitigation

Upgrade MyBB to version 1.8.4 or later. If unable to upgrade, review the group leader notification code paths in the software and implement access control checks to ensure join requests are only sent to the correct group leaders.

Recommended fix High confidence

MyBB 1.8.4

  1. Backup your existing MyBB installation and database before proceeding
  2. Download MyBB 1.8.4 from the official MyBB website or the vendor patch URL
  3. Upload the new MyBB 1.8.4 files to your server, overwriting the existing installation
  4. Run the upgrade script by accessing your forum URL (e.g., http://yourforum.com/install/upgrade.php)
  5. Follow the on-screen upgrade instructions
  6. Verify that the upgrade completed successfully by checking your admin panel and forum functionality
  7. Confirm that group join request notifications are now being sent to the correct group leaders

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mybb Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2015-2786 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data