---
id: "CVE-2026-78189"
kind: "vulnerability"
aliases: ["CVE-2026-78189"]
title: "WebDyne Perl: path traversal runs .psp files outside the document root"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "perl", "psgi", "self-hosted", "webdyne"]
not_affected_if: ["no-psgi-handler", "version-3.022-or-later"]
published_at: "2026-10-31T15:16:54+00:00"
first_seen_at: "2026-10-31T15:36:19+00:00"
updated_at: "2026-10-31T15:36:40+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78189", "first_seen_at": "2026-10-31T15:36:19+00:00"}]
---

# WebDyne Perl: path traversal runs .psp files outside the document root

WebDyne, a Perl PSP template server, versions 3.007 before 3.022 let a remote request with ../ segments reach .psp files outside the document root through the PSGI API route fallback. An attacker who can place or reach a .psp file the server can read can get the embedded Perl code to run.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed WebDyne version with `perl -MWebDyne -e 'print $WebDyne::VERSION'` or `cpanm --info WebDyne` (unknown if the sources do not say which command the vendor uses)
- Confirm whether the app uses the PSGI handler and the API route fallback (unknown if the sources do not say how to confirm this)

## Fix

- WebDyne: move to `3.022` or later (the affected range is 3.007 before 3.022)

## Timeline

- 2026-10-31T15:36:19+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-78189

## From the sources

WebDyne versions from 3.007 before 3.022 for Perl execute .psp files outside the document root via path traversal in the PSGI API route fallback.

When a request matches no file, the PSGI handler retries it as an API route through api_filename. That keeps .. segments in the request path and only checks that the joined path starts with the document root, which a request for /../private passes.

A remote attacker can run the embedded Perl in any .psp file the server can read, such as one uploaded to a directory outside the document root.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_