GHSA-6xxr-648m-gch6 XWiki Platform vulnerable to cross-site request forgery (CSRF) via the REST API

• Maven org.xwiki.platform:xwiki-platform-rest-server: >= 1.8, < 14.10.8 → fixed in 14.10.8 • Maven com.xpn.xwiki.platform:xwiki-core-rest-server: >= 1.8, < 14.10.8 → fixed in 14.10.8 • Maven com.xpn.xwiki.platform:xwiki-rest: >= 1.8, < 14.10.8 → fixed in 14.10.8 • Maven org.xwiki.platform:xwiki-platform-rest-server: >= 15.0-rc-1, < 15.2 → fixed in 15.2

Impact The REST API allows executing all actions via POST requests and accepts `text/plain`, `multipart/form-data` or `application/www-form-urlencoded` as content types which can be sent via regular HTML forms, thus allowing cross-site request forgery. With the interaction of a user with programming rights, this allows remote code execution through script macros and thus impacts the integrity, availability and confidentiality of the whole XWiki installation. For regular cookie-based authentication, the vulnerability is mitigated by SameSite cookie restrictions but as of March 2023, these are not enabled by default in Firefox and Safari. Patches The vulnerability has been patched in XWiki 14.10.8 and 15.2 by requiring a CSRF token header for certain request types that are susceptible to CSRF attacks. Workarounds It is possible to check for the `Origin` header in a reverse proxy to protect the REST endpoint from CSRF attacks, see the Jira issue for an example configuration. References • https://jira.xwiki.org/browse/XWIKI-20135 • https://github.com/xwiki/xwiki-platform/commit/4c175405faa0e62437df397811c7526dfc0fbae7