CVE-2020-26247 : Vulnerability Insights and Analysis

CVE-2020-26247, also known as XXE in Nokogiri, is a vulnerability in the Nokogiri Rubygem that could potentially lead to XXE or SSRF attacks.

Understanding CVE-2020-26247

What is CVE-2020-26247?

Nokogiri, a Rubygem providing various parsers, had an XML External Entity (XXE) vulnerability before version 1.11.0.rc4. This flaw allowed external resources to be accessed over the network, creating a risk for XXE or SSRF attacks.

The Impact of CVE-2020-26247

This vulnerability could be exploited to access external resources over the network, potentially leading to XXE or SSRF attacks. It goes against the security policy of treating all input as untrusted by default.

Technical Details of CVE-2020-26247

Vulnerability Description

The vulnerability in Nokogiri before version 1.11.0.rc4 allowed XML Schemas to be trusted by default, enabling access to external resources and posing a risk for XXE or SSRF attacks.

Affected Systems and Versions

Vendor: sparklemotion
Product: nokogiri
Affected Version: < 1.11.0.rc4

Exploitation Mechanism

The vulnerability allowed malicious actors to exploit XML Schemas parsed by Nokogiri::XML::Schema, potentially enabling XXE or SSRF attacks.

Mitigation and Prevention

Immediate Steps to Take

Update Nokogiri to version 1.11.0.rc4 or later to mitigate the vulnerability.
Monitor for any unusual network activity that could indicate exploitation.

Long-Term Security Practices

Regularly update software and dependencies to patch known vulnerabilities.
Implement input validation and sanitization to prevent XXE and other injection attacks.

Patching and Updates

Refer to the official Nokogiri releases and security advisories for patching guidance and updates.