Upgrading doesn't prevent exploiting vulnerable XWiki documents

QFinch assessment

When an XWiki installation is upgraded and that upgrade contains a fix for a bug in a document, just a new version of that document is added. In some cases, it's still possible to exploit the vulnerability that was fixed in the new version. The severity of this depends on the fixed vulnerability, for the purpose of this advisory take [CVE-2022-36100](https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-2g5c-228j-p52x) as example - it is easily exploitable with just view rights and critical. When XWiki is upgraded from a version before the fix for it (e.g., 14.3) to a version including the fix (e.g., 14.4), the vulnerability can still be reproduced by adding `rev=1.1` to the URL used in the reproduction steps so remote code execution is possible even after upgrading. Therefore, this affects the confidentiality, integrity and availability of the whole XWiki installation. This vulnerability also affects manually added script macros that contained security vulnerabilities that were later fixed by changing the script macro without deleting the versions with the security vulnerability from the history.

Potential impact

When an XWiki installation is upgraded and that upgrade contains a fix for a bug in a document, just a new version of that document is added. In some cases, it's still possible to exploit the vulnerability that was fixed in the new version. The severity of this depends on the fixed vulnerability, for the purpose of this advisory take CVE-2022-36100 as example - it is easily exploitable with just view rights and critical. When XWiki is upgraded from a version before the fix for it (e.g., 14.3) to a version including the fix (e.g., 14.4), the vulnerability can still be reproduced by adding rev=1.1 to the URL used in the reproduction steps so remote code execution is possible even after upgrading. Therefore, this affects the confidentiality, integrity and availability of the whole XWiki installation. This vulnerability also affects manually added script macros that contained security vulnerabilities that were later fixed by changing the script macro without deleting the versions with the security vulnerability from the history. This vulnerability doesn't affect freshly installed versions of XWiki. Further, this vulnerability doesn't affect content that is only loaded from the current version of a document like the code of wiki macros or UI extensions.