Vulnerability in Pyload
CVE-2026-40594
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 · last modified .
CVSS v3 metric
CVSS v3 base score 4.8 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L.
EPSS exploit prediction
EPSS: 0.002 (4.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: -0.000
Affected products
- Pyload — versions < 0.5.0b3.dev98
- Pyload-Ng Project
Weakness classification (CWE)
References
- github.com/pyload/pyload/security/advisories/GHSA-mp82-fmj6-f22v (Exploit, Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-40594?
- CVE-2026-40594 is a medium-severity vulnerability in Pyload, classified under Origin Validation Error. CVSS score: 4.8/10. Published 2026-04-21.
- How severe is CVE-2026-40594?
- Medium severity. CVSS v3 base score is 4.8 out of 10.