docx4j: Stack Overflow via Cyclic `w:basedOn` Style Chain leads to Denial of Service

published 2026-08-17 2 mo ago modified 2026-09-30 39 d ago also GHSA-gc95-3vw8-vg43 , EUVD-2026-77696

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.6%; EPSS 0.6% chance of exploitation in 30 days, percentile 50%
public exploits: 0; none known

docx4j is an open source Java library for creating, editing, and saving OpenXML packages, including DOCX, PPTX, and XLSX files. Prior to 11.5.14, PropertyResolver and adjacent helpers recursively follow the WordprocessingML w:basedOn style inheritance chain without cycle detection. A well-formed DOCX containing mutually based styles causes unbounded recursion in PropertyResolver.fillPPrStack and related effective-style resolution paths, resulting in StackOverflowError. Server-side conversion and table-of-contents processing of an untrusted document can terminate a worker thread, degrade a thread pool, or deny service, although isolation in disposable workers or safe containment of StackOverflowError can reduce the practical effect. The fix adds cyclic-style tracking and CyclicStylesException handling. This issue is fixed in version 11.5.14.

Patch / fix

fixed in 1 links 3

maven org.docx4j:docx4j-core 11.5.14

github.com/plutext/docx4j@47b528c commit
github.com/plutext/docx4j@e06cafb commit
github.com/plutext/docx4j/releases/tag/docx4j-11.5.14 release

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 53 d ago (2026-09-16)

Exploit prediction

0.63% chance of exploitation in the next 30 days, higher than 50% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
maven	org.docx4j:docx4j-core	<11.5.14	11.5.14

Affected products

plutext docx4j
org.docx4j docx4j-core

Classification

Weakness

CWE-674 Uncontrolled Recursion
CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary