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CVE-2018-1311: Apache Xerces-C use-after-free vulnerability processing external DTD

Severity: High

Vendor: The Apache Software Foundation

Versions Affected: Apache Xerces-C XML Parser library (all known versions)

Description: The Xerces-C XML parser contains a use-after-free error
triggered during the scanning of external DTDs.

The bug allows for a denial of service attack in applications that allow
external DTD processing and do not prevent external DTD usage, and could
conceivably result in remote code execution if the heap were groomed.

Mitigation: This flaw has not been addressed in the maintained version
of the library and has no current mitigation other than to disable DTD
processing. This can be accomplished via the DOM using a standard parser
feature, or via SAX using the XERCES_DISABLE_DTD environment variable.

Applications should strongly consider blocking remote entity resolution
and/or disabling of DTD processing in light of the continued
identification of bugs in this area of the library.

Credit: This issue was reported by the UK's National Cyber Security
Centre (NCSC).

References:
http://xerces.apache.org/xerces-c/secadv/CVE-2018-1311.txt

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