Summary
Workarounds
It's possible to workaround the vulnerability by editing the template delete.vm to perform checks on it, but note that the appropriate fix involves new APIs that have been recently introduced in XWiki. See the referenced jira tickets.
References
- Jira ticket about the original vulnerability: https://jira.xwiki.org/browse/XWIKI-20341
- Commit containing the first fix in the template: https://github.com/xwiki/xwiki-platform/commit/e80d22d193df364b07bab7925572720f91a8984a
- Jira ticket about the second part of the vulnerability found after 14.10.5: https://jira.xwiki.org/browse/XWIKI-20672
- Commits containing the second fix in the template:
- Introduction of the macro used for fixing all those vulnerabilities: https://jira.xwiki.org/browse/XWIKI-20583
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
Attribution
This vulnerability has been reported by René de Sain @renniepak.
Impact
Users are able to forge an URL with a payload allowing to inject Javascript in the page (XSS).
It's possible to exploit the delete template to perform a XSS, e.g. by using URL such as:
xwiki/bin/get/FlamingoThemes/Cerulean?xpage=xpart&vm=delete.vm&xredirect=javascript:alert(document.domain)
This vulnerability exists since XWiki 6.0-rc-1.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2023-35156 has a CVSS score of 9.6 (Critical). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (14.10.6, 15.1); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
The vulnerability has been patched in XWiki 14.10.6 and 15.1. Note that a partial patch has been provided in 14.10.5 but wasn't enough to entirely fix the vulnerability.
Frequently Asked Questions
- What is CVE-2023-35156? CVE-2023-35156 is a critical-severity cross-site scripting (XSS) vulnerability in org.xwiki.platform:xwiki-platform-flamingo-skin-resources (maven), affecting versions >= 6.0-rc-1, < 14.10.6. It is fixed in 14.10.6, 15.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2023-35156? CVE-2023-35156 has a CVSS score of 9.6 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of org.xwiki.platform:xwiki-platform-flamingo-skin-resources are affected by CVE-2023-35156? org.xwiki.platform:xwiki-platform-flamingo-skin-resources (maven) versions >= 6.0-rc-1, < 14.10.6 is affected.
- Is there a fix for CVE-2023-35156? Yes. CVE-2023-35156 is fixed in 14.10.6, 15.1. Upgrade to this version or later.
- Is CVE-2023-35156 exploitable, and should I be worried? Whether CVE-2023-35156 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-35156 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-35156?
- Upgrade
org.xwiki.platform:xwiki-platform-flamingo-skin-resourcesto 14.10.6 or later - Upgrade
org.xwiki.platform:xwiki-platform-flamingo-skin-resourcesto 15.1 or later
- Upgrade