Cyber Resilience

CVE-2021-40439

Medium

Published: 07 October 2021

Published
07 October 2021
Modified
21 November 2024
KEV Added
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Patch
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CVSS Score v3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
EPSS Score 0.0029 53.0th percentile
Risk Priority 13 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-40439 is a medium-severity Improper Restriction of XML External Entity Reference (CWE-611) vulnerability in Apache Openoffice. Its CVSS base score is 6.5 (Medium).

Operationally, ranked in the top 47.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

Apache OpenOffice has a dependency on expat software. Versions prior to 2.1.0 were subject to CVE-2013-0340 a "Billion Laughs" entity expansion denial of service attack and exploit via crafted XML files. ODF files consist of a set of XML files.…

more

All versions of Apache OpenOffice up to 4.1.10 are subject to this issue. expat in version 4.1.11 is patched.

CWE(s)
CWE-611

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

apache
openoffice
≤ 4.1.10

Mitigating Controls

Likely Mitigating Controls AI

Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.

CA-8 Penetration Testing
addresses: CWE-611

Penetration testing includes XML external entity payloads, detecting XXE vulnerabilities and enabling their mitigation.

SI-4 System Monitoring
addresses: CWE-611

Identifies XML external entity processing via monitoring of unusual file/network access or resource usage.

References