The chunked upload API (ApiUpload) in MediaWiki before 1.23.11, 1.24.x before 1.24.4, and 1.25.x before 1.25.3 allows remote authenticated users to cause a denial of service (disk consumption) via a file upload using one byte chunks.
{ "availability": "No subscription required", "binaries": [ { "binary_name": "mediawiki", "binary_version": "1:1.27.4-3" }, { "binary_name": "mediawiki-classes", "binary_version": "1:1.27.4-3" } ], "ubuntu_priority": "low" }