CVE-2026-44020: Docling: Unsafe XML Entity Expansion in USPTO Patent Backend
Impact The USPTO patent XML parser used the standard xml.sax.parseString() without protection against XML External Entity (XXE) attacks. An attacker could craft malicious USPTO patent XML files with external entity references that could: - Read arbitrary files from the server filesystem - Perform Server-Side Request Forgery (SSRF) attacks - Cause denial of service through entity expansion (Billion Laughs attack)
The vulnerability affects three USPTO patent format parsers: ICE (v4.x), Grant v2.5, and Application v1.x.
Patches Fixed in version 2.74.0. The parser now uses defusedxml.sax.makeparser() with secure configuration that blocks external entity resolution (featureexternalges=False, featureexternalpes=False) while allowing DTD declarations required by USPTO files. This prevents XXE attacks while maintaining compatibility with the USPTO XML format.
Workarounds Avoid processing USPTO patent XML files from untrusted sources. Implement resource limits (memory, CPU time) when processing patent documents.
References - Fix release: v2.74.0
Other sources
Docling simplifies document processing by parsing diverse formats and providing integrations with the generative AI ecosystem. From 2.13.0 until 2.74.0, the USPTO patent XML parser used the standard xml.sax.parseString() without protection against XML External Entity (XXE) attacks. An attacker could craft malicious USPTO patent XML files with external entity references that could read arbitrary files from the server filesystem, perform Server-Side Request Forgery (SSRF) attacks, or cause denial of service through entity expansion (Billion Laughs attack). The vulnerability affects three USPTO patent format parsers: ICE (v4.x), Grant v2.5, and Application v1.x. This vulnerability is fixed in 2.74.0.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
pip/doclingto a version that resolves this vulnerability.Fixed in 2.74.0 - Upgrade
Upgrade
doclingto a version that resolves this vulnerability.Fixed in 2.74.0 - Configuration
Update the USPTO patent XML parser to use defusedxml.sax.make_parser() with external entity resolution blocked (feature_external_ges=False, feature_external_pes=False) while allowing required DTD declarations for USPTO compatibility.
Docling USPTO patent XML backend (xml.sax.parseString replacement) parser security configuration (defusedxml.sax.make_parser) = feature_external_ges=False, feature_external_pes=False - Configuration
Implement resource limits (memory, CPU time) when processing patent documents to mitigate denial of service from entity expansion (Billion Laughs attack).
Docling USPTO patent document processing resource limits = set memory and CPU time limits - Compensating control
Avoid processing USPTO patent XML files from untrusted sources.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-44020?
The severity of CVE-2026-44020 is high with a CVSS score of 7.5.
How do I fix CVE-2026-44020?
To fix CVE-2026-44020, ensure that you are using a patched version of the affected software, typically version 2.74.0 or later.
What is the impact of CVE-2026-44020?
CVE-2026-44020 allows attackers to exploit XML External Entity (XXE) flaws, potentially reading arbitrary files from the server filesystem.
What software is affected by CVE-2026-44020?
CVE-2026-44020 affects the pip/docling software specifically related to XML parsing functionalities.
What type of attack does CVE-2026-44020 enable?
CVE-2026-44020 enables XML External Entity (XXE) attacks, which can be used for server-side request forgery (SSRF) vulnerabilities.