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Improper Restriction of XML External Entity Reference in org.cyclonedx:cyclonedx-core-java

High
jkowalleck published GHSA-683x-4444-jxh8 Jun 24, 2024

Package

maven org.cyclonedx:cyclonedx-core-java (Maven)

Affected versions

>= 2.1.0, < 9.0.4

Patched versions

9.0.4

Description

Impact

Before deserializing CycloneDX Bill of Materials in XML format, cyclonedx-core-java leverages XPath expressions to determine the schema version of the BOM. The DocumentBuilderFactory used to evaluate XPath expressions was not configured securely, making the library vulnerable to XML External Entity (XXE) injection.

XXE injection can be exploited to exfiltrate local file content, or perform Server Side Request Forgery (SSRF) to access infrastructure adjacent to the vulnerable application.

PoC

import org.cyclonedx.parsers.XmlParser;

class Poc {

    public static void main(String[] args) {
        // Will throw org.cyclonedx.exception.ParseException: java.net.ConnectException: Connection refused
        new XmlParser().parse("""
            <?xml version="1.0" encoding="UTF-8"?>
            <!DOCTYPE bom [<!ENTITY % sp SYSTEM "https://localhost:1010/does-not-exist/file.dtd"> %sp;]>
            <bom xmlns="http://cyclonedx.org/schema/bom/1.5"/>
            """.getBytes());
    }

}

Patches

The vulnerability has been fixed in cyclonedx-core-java version 0.9.4.

Workarounds

If feasible, applications can reject XML documents before handing them to cyclonedx-core-java for parsing.
This may be an option if incoming CycloneDX BOMs are known to be in JSON format.

References

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVE ID

CVE-2024-38374

Weaknesses

Credits