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pyLoad Has Incomplete Fix for CVE-2026-33509 -storage_folder Bypass via Session Directory in pyLoad

Moderate severity GitHub Reviewed Published May 8, 2026 in pyload/pyload • Updated Jun 9, 2026

Package

pip pyload-ng (pip)

Affected versions

<= 0.5.0b3.dev99

Patched versions

None

Description

Summary

The fix for CVE-2026-33509 prevents setting storage_folder inside PKGDIR or userdir, but does NOT protect the Flask session directory (/tmp/pyLoad/flask). An authenticated attacker can set storage_folder to the session directory and download session files of other users via /files/get/, leading to account takeover.

Details

The fix in src/pyload/core/api/__init__.py:

directories = [PKGDIR, userdir]
if any(directories[0].startswith(d) for d in directories[1:]):
    return  # blocked

But the Flask session directory is:

session_storage_path = os.path.join(api.get_cachedir(), "flask")
# = /tmp/pyLoad/flask  ← NOT blocked by fix

Attack Chain

  1. Attacker (admin) sets storage_folder = /tmp/pyLoad/flask
  2. Fix does NOT block this — /tmp/pyLoad/flask not inside PKGDIR or userdir
  3. Attacker requests GET /files/get/<victim_session_filename>
  4. send_from_directory('/tmp/pyLoad/flask', session_file) serves victim's session
  5. Attacker uses stolen session → Account Takeover

PoC

POC

import os

PKGDIR = "/usr/lib/python3/dist-packages/pyload"
userdir = os.path.expanduser("~/.pyload")
session_dir = "/tmp/pyLoad/flask"

correct_case = lambda x: x
directories = [
    correct_case(os.path.join(os.path.realpath(d), ""))
    for d in [session_dir, PKGDIR, userdir]
]
blocked = any(directories[0].startswith(d) for d in directories[1:])

print(f"Fix blocks session_dir: {blocked}")
# Output: Fix blocks session_dir: False  ← BYPASS CONFIRMED

Impact

Authenticated admin can steal sessions of other users → Account Takeover.

Suggested Fix

blocked_dirs = [PKGDIR, userdir, api.get_cachedir()]
directories = [
    os.path.join(os.path.realpath(d), "")
    for d in [value] + blocked_dirs
]
if any(directories[0].startswith(d) for d in directories[1:]):
    return

References

@GammaC0de GammaC0de published to pyload/pyload May 8, 2026
Published to the GitHub Advisory Database May 14, 2026
Reviewed May 14, 2026
Published by the National Vulnerability Database May 28, 2026
Last updated Jun 9, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(14th percentile)

Weaknesses

Use of Incorrectly-Resolved Name or Reference

The product uses a name or reference to access a resource, but the name/reference resolves to a resource that is outside of the intended control sphere. Learn more on MITRE.

CVE ID

CVE-2026-45306

GHSA ID

GHSA-w727-595x-pc3r

Source code

Credits

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