Ubuntu LinuxOperating system · Canonical
CVE-2016-3705
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 · uneditedThe (1) xmlParserEntityCheck and (2) xmlParseAttValueComplex functions in parser.c in libxml2 2.9.3 do not properly keep track of the recursion depth, which allows context-dependent attackers to cause a denial of service (stack consumption and application crash) via a crafted XML document containing a large number of nested entity references.
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 confidenceThe vulnerability exists in libxml2 2.9.3's xmlParserEntityCheck and xmlParseAttValueComplex functions in parser.c, which fail to properly track recursion depth when processing nested XML entity references. This allows attackers to cause stack exhaustion and application crash via specially crafted XML documents with deep entity nesting.
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
Ubuntu LinuxOperating system
= 12.04= 14.04= 15.10= 16.04
Debian LinuxOperating system
= 8.0= 2.9.3= 3.0= 3.0= 42.1CVSS 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:3.0/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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Check installed libxml2 versionRun 'dpkg -l libxml2' on Debian/Ubuntu, 'rpm -q libxml2' on RHEL/SUSE, or 'xml2-config --version' to query the library version directlyAffected if The reported version is exactly 2.9.3
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Verify libxml2 library fileCheck for the presence of libxml2 shared library file such as /usr/lib/x86_64-linux-gnu/libxml2.so.2 or locate libxml2.so* on the systemAffected if libxml2 version 2.9.3 library files exist on the system
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Identify applications using libxml2Run 'ldd' on suspected binaries or check application dependencies to see if they link against libxml2, or search for xmlParse or xmlRead functions in application code if source is availableAffected if Applications that parse XML are linked against the vulnerable libxml2 library
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Confirm XML entity processing capabilityReview application configurations or test with a benign XML document containing entity references (&entity;) to verify the parser expands entitiesAffected if The application processes XML with entity references using libxml2
The system is affected if libxml2 version 2.9.3 is installed and any application on the system uses it to parse XML documents containing nested entity references.
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 libxml2 to a patched version (2.9.4 or later) that implements proper recursion depth limiting, or implement application-level XML complexity limits if library upgrade is not feasible.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation3.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,896.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-3705 — 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-2016-3705 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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- Version or environment caveats, and links to real fixes
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