GHSA-g4h6-qp44-wqvx XWiki.WebHome vulnerable to Improper Privilege Management in XWiki resolving groups

• Maven org.xwiki.platform:xwiki-platform-oldcore: >= 11.3.7, < 13.10.4 → fixed in 13.10.4 • Maven org.xwiki.platform:xwiki-platform-oldcore: >= 14.0-rc-1, < 14.2-rc-1 → fixed in 14.2-rc-1

Impact It's possible to exploit a bug in XWikiRights resolution of groups to obtain privilege escalation. More specifically, editing a right with the object editor leads to adding a supplementary empty value to groups which is then resolved as a reference to XWiki.WebHome page. Adding an XWikiGroup xobject to that page then transforms it to a group, any user put in that group would then obtain the privileges related to the edited right. Note that this security issue is normally mitigated by the fact that XWiki.WebHome (and XWiki space in general) should be protected by default for edit rights. Patches The problem has been patched in XWiki 13.10.4 and 14.2RC1 to not consider anymore empty values in XWikiRights. Workarounds It's possible to workaround the problem by setting appropriate rights on XWiki.WebHome page to prevent users to edit it. References • https://jira.xwiki.org/browse/XWIKI-18386 • https://jira.xwiki.org/browse/XWIKI-15776 For more information If you have any questions or comments about this advisory: • Open an issue in Jira XWiki.org • Email us at Security Mailing List