# CVE-2026-40594

> Vulnerability · severity: **MEDIUM** (CVSS 4.8).

## Description

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev98, the set_session_cookie_secure before_request handler in src/pyload/webui/app/__init__.py reads the X-Forwarded-Proto header from any HTTP request without validating that the request originates from a trusted proxy, then mutates the global Flask configuration SESSION_COOKIE_SECURE on every request. Because pyLoad uses the multi-threaded Cheroot WSGI server (request_queue_size=512), this creates a race condition where an attacker's request can influence the Secure flag on other users' session cookies — either downgrading cookie security behind a TLS proxy or causing a session denial-of-service on plain HTTP deployments. This vulnerability is fixed in 0.5.0b3.dev98.

## Key facts

- **CVE ID:** CVE-2026-40594
- **Published:** 2026-04-21
- **CVSS severity:** MEDIUM
- **CVSS base score:** 4.8
- **CWE codes:** CWE-346

## Affected products

- `pyload-ng_project:pyload-ng`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40594

## Citation

> AI Analytics. CVE-2026-40594. Retrieved 2026-07-24 from https://api.ai-analytics.org/cve/CVE-2026-40594. Derived from NIST NVD. Licensed CC0.

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