YaCy Search Server through 1.941 contains an XML external entity injection vulnerability in SVG, FreeMind, and OpenSearch parsers that fail to disable external entity resolution. Attackers can publish malicious documents with DOCTYPE declarations containing SYSTEM entities pointing to local files, causing the crawler to exfiltrate file contents into the searchable index.

YaCy Search Server through version 1.941 is affected by an XML External Entity (XXE) injection vulnerability. The flaw exists in three parsers: SVG, FreeMind, and OpenSearch, which fail to disable external entity resolution. Attackers can craft malicious documents with DOCTYPE declarations referencing SYSTEM entities that point to local files on the server. When the YaCy crawler processes these documents, it inadvertently exfiltrates local file contents into the searchable index, exposing sensitive data. The vulnerability allows unauthorized access to local filesystem contents through the crawler mechanism. A fix has been committed to the repository. Multiple parser source files are identified as vulnerable, including svgParser.java, mmParser.java, and opensearchdescriptionReader.java. The issue is tracked publicly via GitHub issue #818 and has been reported by VulnCheck.