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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.

PUBLISHED Reserved 2026-04-14 | Published 2026-04-21 | Updated 2026-04-21 | Assigner GitHub_M




MEDIUM: 4.8CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L

Problem types

CWE-346: Origin Validation Error

Product status

< 0.5.0b3.dev98
affected

References

github.com/...pyload/security/advisories/GHSA-mp82-fmj6-f22v exploit

github.com/...pyload/security/advisories/GHSA-mp82-fmj6-f22v

cve.org (CVE-2026-40594)

nvd.nist.gov (CVE-2026-40594)

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