MoodleCMS
CVE-2015-5267
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 · uneditedlib/moodlelib.php in Moodle through 2.6.11, 2.7.x before 2.7.10, 2.8.x before 2.8.8, and 2.9.x before 2.9.2 relies on the PHP mt_rand function to implement the random_string and complex_random_string functions, which makes it easier for remote attackers to predict password-recovery tokens via a brute-force approach.
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 confidenceMoodle's random_string and complex_random_string functions in lib/moodlelib.php use PHP's mt_rand() for generating password-recovery tokens. The Mersenne Twister PRNG used by mt_rand() is predictable when enough outputs are observed, allowing attackers to brute-force recovery tokens by predicting the sequence.
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
MoodleCMS
<= 2.6.11= 2.7.0= 2.7.1= 2.7.2= 2.7.3= 2.7.4= 2.7.5= 2.7.6= 2.7.7= 2.7.8= 2.7.9= 2.8.0CVSS 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
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 checksWork through these to decide whether this CVE applies to you.
-
Check Moodle versionLocate the version.php file in your Moodle installation (usually in version.php in the root directory) or access the admin page that displays the version. Compare your version number against the affected list: <= 2.6.11, 2.7.0 through 2.7.9, or 2.8.0Affected if Your installed version matches any of the affected versions listed
-
Inspect random_string function in lib/moodlelib.phpOpen lib/moodlelib.php in a text editor or use grep to search: grep -n 'function random_string' lib/moodlelib.php. Examine the function implementation to see if it calls mt_rand()Affected if The random_string function contains a call to mt_rand() for generating random characters
-
Inspect complex_random_string function in lib/moodlelib.phpOpen lib/moodlelib.php and locate the complex_random_string function (grep -n 'function complex_random_string'). Examine whether it uses mt_rand() for token generationAffected if The complex_random_string function uses mt_rand() instead of a cryptographically secure random source
-
Verify password recovery is enabledCheck Moodle admin settings at Site Administration > Plugins > Authentication > Manage Authentication. Confirm that the 'Password recovery' or 'Forgot password' feature is enabled, or inspect the auth/email/config.php fileAffected if Password recovery functionality is active - the vulnerable functions are only exploitable when password reset tokens can be generated
You are affected if your Moodle version is 2.7.0-2.7.9, 2.8.0, or <=2.6.11 AND the lib/moodlelib.php file still uses mt_rand() in the random_string or complex_random_string functions AND password recovery is enabled.
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 a patched Moodle version (2.7.10+, 2.8.8+, or 2.9.2+) which replaces mt_rand() with cryptographically secure random number generation. If immediate patching is not possible, monitor for anomalous password-reset activity.
Fix this in Moodle
Scoped from the published advisory
- 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-2015-5267 — 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-2015-5267 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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