Vulnerability: Cross-site Scripting in wiki manager join wiki page ### Impact
We found a possible XSS vector in the `WikiManager.JoinWiki ` wiki page related to the "requestJoin" field.

### Patches
The issue is patched in versions 12.10.11, 14.0-rc-1, 13.4.7, 13.10.3.

### Workarounds
The easiest workaround is to edit the wiki page `WikiManager.JoinWiki` (with wiki editor) and change the line

```
<input type='hidden' name='requestJoin' value="$!request.requestJoin"/>
```

into

```
<input type='hidden' name='requestJoin' value="$escapetool.xml($!request.requestJoin)">
```

### References
  * https://jira.xwiki.org/browse/XWIKI-19292
  * https://github.com/xwiki/xwiki-platform/commit/27f839133d41877e538d35fa88274b50a1c00b9b

### For more information
If you have any questions or comments about this advisory:
* Open an issue in [Jira XWiki](https://jira.xwiki.org)
* Email us at [security mailing list](mailto:security@xwiki.org)
Vulnerability ID: GHSA-ph5x-h23x-7q5q
CWE: CWE-79
Severity score: 7.4
Project: https://github.com/xwiki/xwiki-platform
Published: 2022-05-25
File: xwiki-platform-core/xwiki-platform-wiki/xwiki-platform-wiki-ui/xwiki-platform-wiki-ui-mainwiki/src/main/resources/WikiManager/JoinWiki.xml
Commit message: XWIKI-19292: Fix bad escaping
Commit author: Thomas Mortagne

Vulnerable version (before fix):
                   &lt;a href="$backUrl" class='button secondary'&gt;{{translation key="platform.wiki.users.join.request.cancel.label"/}}&lt;/a&gt;                 &lt;/span&gt;                 &lt;input type='hidden' name='wikiId' value="$!wikiId"/&gt;                 &lt;input type='hidden' name='requestJoin' value="$!request.requestJoin"/&gt;                 &lt;input type="hidden" name="form_token" value="$!escapetool.xml($services.csrf.getToken())" /&gt;               &lt;/dl&gt;             &lt;/form&gt;

Fixed version (after fix):
                   &lt;a href="$backUrl" class='button secondary'&gt;{{translation key="platform.wiki.users.join.request.cancel.label"/}}&lt;/a&gt;                 &lt;/span&gt;                 &lt;input type='hidden' name='wikiId' value="$!wikiId"/&gt;                 &lt;input type='hidden' name='requestJoin' value="$escapetool.xml($!request.requestJoin)"/&gt;                 &lt;input type="hidden" name="form_token" value="$!escapetool.xml($services.csrf.getToken())" /&gt;               &lt;/dl&gt;             &lt;/form&gt;

Patch:
patch: @@ -245,7 +245,7 @@
                   &lt;a href="$backUrl" class='button secondary'&gt;{{translation key="platform.wiki.users.join.request.cancel.label"/}}&lt;/a&gt;
                 &lt;/span&gt;
                 &lt;input type='hidden' name='wikiId' value="$!wikiId"/&gt;
-                &lt;input type='hidden' name='requestJoin' value="$!request.requestJoin"/&gt;
+                &lt;input type='hidden' name='requestJoin' value="$escapetool.xml($!request.requestJoin)"/&gt;
                 &lt;input type="hidden" name="form_token" value="$!escapetool.xml($services.csrf.getToken())" /&gt;
               &lt;/dl&gt;
             &lt;/form&gt;
path: xwiki-platform-core/xwiki-platform-wiki/xwiki-platform-wiki-ui/xwiki-platform-wiki-ui-mainwiki/src/main/resources/WikiManager/JoinWiki.xml