Summary
XWiki Platform Old Core: Resource path traversal via /skin/ action endpoint in Jetty 12+
Workarounds
A possible workaround is to use a different application server, like Jetty < 12 (in the case of XWiki < 17) or Tomcat, which don't seem to be impacted.
Resources
For more information
If there are any questions or comments about this advisory:
- Open an issue in Jira XWiki.org
- Send an email to the Security Mailing List
Attribution
Lê Ngọc Khoa reported the vulnerability.
Impact
With Jetty 12+ a user can craft a URL to access any resource the Jetty instance is allowed to access.
For example http://[host]/xwiki/bin/skin/..%252f/..%252f..%252f..%252f..%252f..%252f..%252f..%252fetc/passwd allows downloading the content of the /etc/passwd file, provided Jetty is allowed to read it, and if your XWiki webapp is located exactly 5 levels below / (like /var/lib/jetty/webapps/xwiki, which is the case in the docker image, for example).
Another example which does not go out of the XWiki webapp, but it's still a vulnerability (since users should not be allowed to access Hibernate or XWiki configuration files) is http://[host]/xwiki/bin/skin/..%252f/..%252fWEB-INF/xwiki.cfg.
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.
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This vulnerability has been patched in XWiki 17.10.5 and 18.2.0.
Frequently Asked Questions
- What is CVE-2026-34151? CVE-2026-34151 is a high-severity security vulnerability in org.xwiki.platform:xwiki-platform-oldcore (maven), affecting versions < 17.10.5. It is fixed in 17.10.5, 18.2.0.
- Which versions of org.xwiki.platform:xwiki-platform-oldcore are affected by CVE-2026-34151? org.xwiki.platform:xwiki-platform-oldcore (maven) versions < 17.10.5 is affected.
- Is there a fix for CVE-2026-34151? Yes. CVE-2026-34151 is fixed in 17.10.5, 18.2.0. Upgrade to this version or later.
- Is CVE-2026-34151 exploitable, and should I be worried? Whether CVE-2026-34151 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-2026-34151 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-2026-34151?
- Upgrade
org.xwiki.platform:xwiki-platform-oldcoreto 17.10.5 or later - Upgrade
org.xwiki.platform:xwiki-platform-oldcoreto 18.2.0 or later
- Upgrade