CVE-2026-34151

CVE-2026-34151 is a high-severity vulnerability with a CVSS 4.0 base score of 8.2. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-24.

Key facts

Description

XWiki Platform is a generic wiki platform. Prior to 17.10.5 and 18.2.0, the /skin/ action in com.xpn.xwiki.web.SkinAction can resolve double-encoded parent-directory segments outside the intended skin or web-application resource prefix when Jetty 12 or later decodes the request path. The affected lookup is replaced with Environment.getResourceAsStream(String, String), which constrains a resource to its expected prefix. An unauthenticated remote attacker can use the vulnerable behavior to read arbitrary resources permitted to the Jetty process, including WEB-INF/xwiki.cfg and, depending on deployment depth and operating-system permissions, host files. Tomcat and Jetty versions before 12 do not appear affected. This issue is fixed in versions 17.10.5 and 18.2.0.

Frequently asked questions

What is CVE-2026-34151?
XWiki Platform is a generic wiki platform. Prior to 17.10.5 and 18.2.0, the /skin/ action in com.xpn.xwiki.web.SkinAction can resolve double-encoded parent-directory segments outside the intended skin or web-application resource prefix when Jetty 12 or later decodes the request path. The affected lookup is replaced with Environment.getResourceAsStream(String, String), which constrains a resource to its expected prefix. An unauthenticated remote attacker can use the vulnerable behavior to read arbitrary resources permitted to the Jetty process, including WEB-INF/xwiki.cfg and, depending on deployment depth and operating-system permissions, host files. Tomcat and Jetty versions before 12 do not appear affected. This issue is fixed in versions 17.10.5 and 18.2.0.
How severe is CVE-2026-34151?
CVE-2026-34151 has a CVSS 4.0 base score of 8.2, rated high severity.
Is CVE-2026-34151 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-34151?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-34151 published?
CVE-2026-34151 was published on 2026-09-14 and last updated on 2026-09-30.

References

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