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

> Unauthenticated attackers can read arbitrary files via path traversal in XWiki when running on Jetty 12+, exposing sensitive configuration and host files.

- **Severity:** High 8.2 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Sep 2026
- **Updated:** 14 Sep 2026
- **Also known as:** GHSA-qj4x-9g63-25g6

## What is CVE-2026-34151?

CVE-2026-34151 is a high-severity path traversal vulnerability in xwiki-platform, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-24 (Path Traversal: '../filedir')

## Which versions are affected by CVE-2026-34151?

4 open source packages ship an affected version, including org.xwiki.platform:xwiki-platform-oldcore.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `org.xwiki.platform:xwiki-platform-oldcore` | Maven | All versions | 17.10.5 |
| `org.xwiki.platform:xwiki-platform-oldcore` | Maven | All versions | 17.10.5 |
| `org.xwiki.platform:xwiki-platform-oldcore` | Maven | From 18.0.0-rc-1 | 18.2.0 |
| `org.xwiki.platform:xwiki-platform-oldcore` | Maven | From 18.0.0-rc-1 | 18.2.0 |

## How do I fix CVE-2026-34151?

Upgrade org.xwiki.platform:xwiki-platform-oldcore to a fixed version for your release line: 17.10.5 or 18.2.0.

## Is CVE-2026-34151 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34151 exists.

Public exploit code:

- XWiki Platform - Path Traversal (nuclei): http/cves/2026/CVE-2026-34151.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34151 and fix it if it is affected.

What it is: CVE-2026-34151 is a high-severity path traversal vulnerability in xwiki-platform, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-34151 exists.

Affected packages and fixed versions:
- org.xwiki.platform:xwiki-platform-oldcore (Maven): affected all versions; fixed in 17.10.5
- org.xwiki.platform:xwiki-platform-oldcore (Maven): affected all versions; fixed in 17.10.5
- org.xwiki.platform:xwiki-platform-oldcore (Maven): affected from 18.0.0-rc-1; fixed in 18.2.0
- org.xwiki.platform:xwiki-platform-oldcore (Maven): affected from 18.0.0-rc-1; fixed in 18.2.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34151/ (Markdown: https://insights.sbomify.com/CVE-2026-34151/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34151
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34151
- OSV: https://osv.dev/vulnerability/CVE-2026-34151

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34151/
Summaries are generated and may contain mistakes; the official description above is the record.