CVE-2021-40511
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 · uneditedOBDA systems’ Mastro 1.0 is vulnerable to XML Entity Expansion (aka “billion laughs”) attack allowing denial of service.
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 confidenceMastro 1.0 is vulnerable to XML Entity Expansion (billion laughs) attacks. The vulnerability allows attackers to send malicious XML input containing recursive entity definitions that expand exponentially during parsing, consuming excessive server CPU and memory resources and causing denial of service.
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= 1.0CVSS 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
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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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Verify Mastro versionIdentify the installed version of Mastro by checking the application binaries, package metadata, or version information file. For example, check the application's about dialog, installed package details, or any version.txt file in the installation directory.Affected if The installed version is exactly 1.0 (Mastro = 1.0)
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Confirm XML parsing is in useCheck if Mastro is configured to process XML input by examining configuration files, XML import features, or data transformation settings within the Mastro application.Affected if XML parsing or XML data import/processing features are enabled or actively used
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Inspect XML parser entity expansion settingsExamine the XML parser configuration files or settings used by Mastro. Look for parser options related to DOCTYPE, entity expansion, or external entity processing. Check whether features like 'disallow-doctype-decl', 'max-general-entities-size-limit', or similar resource limits are configured.Affected if The XML parser has entity expansion enabled or no resource limits are configured for entity definitions
You are affected if you are running Mastro version 1.0, process XML input, and your XML parser configuration does not disable or limit entity expansion.
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 dataDisable or limit XML entity expansion in the XML parser configuration, implement parser-level resource limits, and validate/sanitize XML input before processing. Consider upgrading to a patched version if available.
- Consultation2.0 h
- Implementation4.0 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-2021-40511 — 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-2021-40511 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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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