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docling-project/docling · Security

Docling: Unsafe Archive Extraction and XML Parsing in METS-GBS Backend

GHSA ID
GHSA-r3xg-rg9j-67fv
CVE ID
CVE-2026-44018
Severity
medium
Published
Updated
CVSS
5.5 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS v3
5.5 · CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Description

Impact

The METS-GBS backend's XML parsing and the input document format detection lacked security controls, enabling:

  • XML External Entity (XXE) attacks to read local files or cause denial of service
  • Decompression bombs (zip bombs) to exhaust memory and disk space
  • Unbounded archive extraction consuming system resources

An attacker could craft malicious METS-GBS archives that, when processed, could read sensitive files, exhaust system resources, or cause application crashes.

Patches

Fixed in version 2.91.0. The fix implements:

  • Secure XML parsing with resolve_entities=False, load_dtd=False, and no_network=True
  • Configurable limits: 300 MB total extraction size, 10 MB per file, 1000 member count
  • Cumulative size tracking across all extractions
  • Early termination when limits are exceeded
  • Secure format detection of METS-GBS tar archives with _detect_mets_gbs() method: maximum file size (10 MB per file), maximum member count (1000 members), and exception handling to gracefully fail when limits are exceeded

Workarounds

Avoid processing METS-GBS archives from untrusted sources. If necessary, pre-validate archives in an isolated environment with resource limits.

References

CWEs

  • CWE-409 · Improper Handling of Highly Compressed Data (Data Amplification)
  • CWE-611 · Improper Restriction of XML External Entity Reference
  • CWE-776 · Improper Restriction of Recursive Entity References in DTDs ('XML Entity Expansion')

References