Merge SystemApplication · Mybb

CVE-2015-8975

MEDIUM · 6.1 CVSS v3.0 Published 2017-01-31
Fix available
A fix is available. Upgrade to after 1.6.17 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges

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
Cross-site scripting (XSS) vulnerability in the error handler in MyBB (aka MyBulletinBoard) before 1.6.18 and 1.8.x before 1.8.6 and MyBB Merge System before 1.8.6 might allow remote attackers to inject arbitrary web script or HTML via unspecified vectors.

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 · high confidence

Cross-site scripting (XSS) vulnerability in the error handler of MyBB (MyBulletinBoard) allows remote attackers to inject arbitrary web script or HTML via unspecified vectors in error message output before versions 1.6.18 and 1.8.6.

MitigationUpgrade MyBB to version 1.6.18 or 1.8.6 or later, which contains the patched error handler that properly sanitizes output.

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
Merge SystemApplication
Affected:= 1.8.5
MybbApplication
Affected:<= 1.6.17= 1.8.0= 1.8.1= 1.8.2= 1.8.3= 1.8.4= 1.8.5

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
Privileges
None
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

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. Locate installed MyBB version
    Access the MyBB admin control panel and navigate to the Dashboard or Home section, which typically displays the current software version. Alternatively, check for a version file in the MyBB installation directory.
    Affected if The displayed version is 1.6.17 or lower, or any version from 1.8.0 through 1.8.5, or 1.8.5 for the MyBB Merge System.
  2. Confirm MyBB core product
    Verify that the installation is the main MyBB forum software rather than a third-party plugin or theme. The vulnerability exists in the MyBB core error handler, not in add-ons.
    Affected if The product is MyBB core and the version falls within the affected ranges.
  3. Identify error handler usage
    The MyBB error handler is a core component that processes and displays error messages throughout the software. It is active by default in any standard MyBB installation.
    Affected if The error handler is enabled and processing user-supplied input that could trigger error conditions.
  4. Compare against affected version list
    Cross-reference your installed version number with the known vulnerable versions: MyBB <= 1.6.17, MyBB 1.8.0-1.8.5, or MyBB Merge System 1.8.5.
    Affected if Your installed version matches any of these vulnerable versions.

You are affected if your MyBB installation runs version 1.6.17 or lower, or any version from 1.8.0 to 1.8.5, and the error handler is processing unsanitized error output.

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.

From vendor data
Upgrade available Upgrade to a release after 1.6.17
Interim mitigation

Upgrade MyBB to version 1.6.18 or 1.8.6 or later, which contains the patched error handler that properly sanitizes output.

Fix this in Merge System Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,904.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2015-8975 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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-2015-8975 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