GHSA-62pr-qqf7-hh89 XWiki Platform vulnerable to remote code execution through the section parameter in Administration as guest

• Maven org.xwiki.platform:xwiki-platform-administration-ui: < 14.10.14 → fixed in 14.10.14 • Maven org.xwiki.platform:xwiki-platform-administration-ui: >= 15.0-rc-1, < 15.5.1 → fixed in 15.5.1 • Maven org.xwiki.platform:xwiki-platform-administration: < 14.10.14 → fixed in 14.10.14

Impact XWiki doesn't properly escape the section URL parameter that is used in the code for displaying administration sections. This allows any user with read access to the document `XWiki.AdminSheet` (by default, everyone including unauthenticated users) to execute code including Groovy code. This impacts the confidentiality, integrity and availability of the whole XWiki instance. By opening the URL `/xwiki/bin/get/Main/WebHome?sheet=XWiki.AdminSheet&viewer=content&section=%5D%5D%7B%7B%2Fhtml%7D%7D%7B%7Basync%7D%7D%7B%7Bgroovy%7D%7Dservices.logging.getLogger(%22attacker%22).error(%22Attack%20succeeded!%22)%7B%7B%2Fgroovy%7D%7D%7B%7B%2Fasync%7D%7D&xpage=view` where `` is the URL of the XWiki installation, it can be tested if an XWiki installation is vulnerable. If this causes a log message `ERROR attacker - Attack succeeded!` to appear in XWiki's log, the installation is vulnerable. In very old versions of XWiki, the attack can be demonstrated with `/xwiki/bin/get/XWiki/XWikiPreferences?section=%3C%25println(%22Hello%20from%20Groovy%22)%25%3E&xpage=view` which displays `admin.hello from groovy` as title when the attack succeeds (tested on XWiki 1.7). Patches This vulnerability has been patched in XWiki 14.10.14, 15.6 RC1 and 15.5.1. Workarounds The fix, which consists of replacing `= $services.localization.render("administration.sectionTitle$level", [$sectionName]) =` by `= $services.localization.render("administration.sectionTitle$level", 'xwiki/2.1', [$sectionName]) =`, can be applied manually to the document `XWiki.AdminSheet`. References • https://jira.xwiki.org/browse/XWIKI-21110 • https://github.com/xwiki/xwiki-platform/commit/fec8e0e53f9fa2c3f1e568cc15b0e972727c803a