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CVE-2016-9180: XML Twig For Perl: Improper Restriction of XML External Entity Reference

CVE-2016-9180 is rated critical with a CVSS v3.0 base score of 9.1 and NVD lists XML Twig For Perl as the affected product. Per its scoring, it can be exploited over the network, without authentication, without any user interaction.

Vulnerability description

perl-XML-Twig: The option to `expand_external_ents`, documented as controlling external entity expansion in XML::Twig does not work. External entities are always expanded, regardless of the option's setting.

Severity breakdown

CVSS v3.0 9.1: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

• Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
• Attack complexity: Low. No special conditions; the attack can be repeated reliably.
• Privileges required: None. No account or prior access is needed.
• User interaction: None. No action from any user is needed.
• Scope: Unchanged. Impact stays within the vulnerable component.
• Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
• Integrity impact: None. No loss of integrity.
• Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-611: Improper Restriction of XML External Entity Reference

The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

Affected products

• XML Twig For Perl: all versions listed by NVD

References

• http://www.openwall.com/lists/oss-security/2016/11/04/2
• http://www.securityfocus.com/bid/94219
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00020.html
• http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00033.html