CVE-2021-40849
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 · uneditedIn Mahara before 20.04.5, 20.10.3, 21.04.2, and 21.10.0, the account associated with a web services token is vulnerable to being exploited and logged into, resulting in information disclosure (at a minimum) and often escalation of privileges.
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 confidenceIn Mahara before the patched versions, the account associated with a web services token can be exploited, allowing an attacker to log into that account. This results in unauthorized access to the account's data (information disclosure) and often enables privilege escalation, as the attacker can assume the identity and permissions of the token holder.
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< 20.04.5>= 20.10.0, < 20.10.3>= 21.04.0, < 21.04.2= 21.10.0CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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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Determine installed Mahara versionLocate the version file in your Mahara installation (typically htdocs/lib/version.php or check the admin interface under Site administration > Overview), or run: grep -r 'version' htdocs/lib/version.php | head -5Affected if The installed version is < 20.04.5, or >= 20.10.0 but < 20.10.3, or >= 21.04.0 but < 21.04.2, or exactly 21.10.0
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Verify if web services are enabledNavigate to Site administration > Web services > Overview, or inspect the database table 'artefact_plugin_web_services' or 'auth_plugin' configuration for web services pluginsAffected if Web services plugins (SOAP, XML-RPC, REST, OAuth) are installed and enabled in the Mahara installation
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Check for existing web services tokensQuery the database table 'usr_session' or 'external_tokens' for active web services tokens, or check Site administration > Web services > Manage tokensAffected if There are active web services tokens present in the system that could be exploited
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Review web services token ownershipExamine the user accounts associated with any active tokens and assess their privilege level, particularly tokens belonging to admin or high-privilege usersAffected if Tokens exist for administrative or privileged user accounts, which would allow privilege escalation if exploited
Your Mahara instance is affected if it runs a version matching the ranges above AND has web services functionality enabled with active tokens present.
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.
dbcve · scoped20.04.520.10.321.04.2
Update Mahara to version 20.04.5, 20.10.3, 21.04.2, or 21.10.0 or later to remediate this vulnerability.
Upgrade to Mahara 20.04.5, 20.10.3, 21.04.2, or later stable release (21.10.1+)
- 1. Back up your Mahara database and files directory before proceeding
- 2. Download the appropriate fixed version from the official Mahara download page (mahara.org)
- 3. Place your site in maintenance mode via Site Administration > General Settings > Maintenance mode
- 4. Replace the Mahara application files with the new version, preserving your config.php and any local customizations
- 5. Run the upgrade script by accessing the site URL (e.g., https://your-mahara-site.com/upgrade.php)
- 6. Follow the on-screen upgrade instructions
- 7. Verify the upgrade completed successfully and test critical functionality
- 8. Disable maintenance mode once verified
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40849 — 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-2021-40849 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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