Ubuntu LinuxOperating system · Canonical
CVE-2018-14404
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 · uneditedA NULL pointer dereference vulnerability exists in the xpath.c:xmlXPathCompOpEval() function of libxml2 through 2.9.8 when parsing an invalid XPath expression in the XPATH_OP_AND or XPATH_OP_OR case. Applications processing untrusted XSL format inputs with the use of the libxml2 library may be vulnerable to a denial of service attack due to a crash of the application.
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 confidenceA NULL pointer dereference vulnerability exists in xmlXPathCompOpEval() in libxml2 through 2.9.8 when parsing invalid XPath expressions in the XPATH_OP_AND or XPATH_OP_OR case. Applications processing untrusted XSL format inputs using libxml2 can be crashed via a specially crafted XPath expression, leading to 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
Ubuntu LinuxOperating system
= 12.04= 14.04= 16.04= 18.04
Debian LinuxOperating system
all versions<= 2.9.8CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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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Identify libxml2 versionRun 'xml2-config --version' or check the package manager: 'dpkg -l | grep libxml2' on Debian/Ubuntu, or 'rpm -qa | grep libxml2' on RHEL-based systemsAffected if The installed version is 2.9.8 or lower
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Locate libxml2 library fileCheck for libxml2 shared library: 'find /usr -name "libxml2.so*" 2>/dev/null' and note the file pathAffected if A library file exists and its version (shown by 'strings libxml2.so.* | grep "^2\." | head -1' or from the filename) is 2.9.8 or earlier
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Identify applications using libxml2Review application dependencies: 'ldd /path/to/application | grep libxml2' or check application documentation for libxml2 usageAffected if The application links against libxml2 and processes XSL or XPath data
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Determine if untrusted XSL input is processedInspect application configuration and code for XSL processing functions (xsltProcess, xsltApplyStylesheet, xmlXPathEval, etc.) that handle external or untrusted inputAffected if The application accepts XSL/XPath input from untrusted sources without prior validation
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Test XPath expression parsingIf you have access to the application or a test environment, attempt to evaluate a crafted XPath expression containing invalid constructs with XPATH_OP_AND or XPATH_OP_OR operationsAffected if The application crashes or hangs when processing malformed XPath expressions
You are affected if your system runs libxml2 version 2.9.8 or earlier AND an application processes untrusted XSL/XPath input using the vulnerable library.
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 version 2.9.9 or later which contains the fix. If immediate patching is not feasible, implement input validation to reject malformed XPath expressions before passing to libxml2, and restrict processing of untrusted XSL inputs where possible.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,656.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-14404 — 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-2018-14404 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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