CVE-2011-5131
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 · uneditedCross-site request forgery (CSRF) vulnerability in global.php in MyBB before 1.6.5 allows remote attackers to hijack the authentication of a user for requests that change the user's language via the language parameter.
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 confidenceCross-site request forgery (CSRF) vulnerability in MyBB's global.php allows remote attackers to change a logged-in user's language preference by tricking them into visiting a malicious page. The language parameter is not protected with anti-CSRF tokens, enabling attackers to forge requests on behalf of authenticated users.
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<= 1.6.4= 1.1.0= 1.1.1= 1.1.2= 1.1.3= 1.1.4= 1.1.5= 1.1.6= 1.1.7= 1.1.8= 1.2= 1.2.0CVSS 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
- M
- Authentication
- None
- Confidentiality
- Partial
- Integrity
- Partial
- Availability
- Partial
AV:N/AC:M/Au:N/C:P/I:P/A:P
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 checksWork through these to decide whether this CVE applies to you.
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Identify MyBB versionCheck the version.php file in your MyBB root directory, or view the version number in the Admin Control Panel under 'Home' > 'Dashboard' or 'Forum Settings' > 'Board Settings'. The version is typically displayed on the admin dashboard.Affected if Your installed version is 1.6.4 or lower, or matches 1.1.0 through 1.1.8, 1.2, or 1.2.0.
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Locate global.phpNavigate to the MyBB root directory and locate the file named 'global.php'. This is the core file that handles language preference changes.Affected if The file exists and your version is in the affected range.
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Check language change code in global.phpOpen global.php and search for code handling the 'language' or 'lang' parameter. Look for where the language preference is processed, typically near where user preferences are set. Examine whether anti-CSRF tokens (such as 'my_post_key' or similar token checks) are validated before accepting the language parameter.Affected if The language parameter is processed without validating an anti-CSRF token or post key.
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Verify session requirementConfirm that the language change functionality requires an authenticated user session. The CSRF attack only affects logged-in users whose language preference can be silently changed.Affected if The language change can be triggered for authenticated users without token validation.
You are affected if your MyBB installation version is 1.6.4 or lower, or falls within the 1.1.x to 1.2.x range, and the language change functionality in global.php lacks anti-CSRF token validation.
Generated from the published advisory. Verify against your own configuration.
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 dataUpgrade to MyBB 1.6.5 or later, which includes CSRF protection for the language change functionality. Alternatively, implement anti-CSRF tokens for the language parameter in global.php.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2011-5131 — 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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2011-5131 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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