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🛡️ CVE-2026-41133 — pyload

🟠 CVSS 8.8 — High ⚠️ Exploit Public CWE-613 NVD
8.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

pyLoad has Stale Session Privilege After Role/Permission Change (Privilege Revocation Bypass)

Summary

pyLoad caches role and permission in the session at login and continues to authorize requests using these cached values, even after an admin changes the user's role/permissions in the database.

As a result, an already logged-in user can keep old (revoked) privileges until logout/session expiry, enabling continued privileged actions.

This is a core authorization/session-consistency issue and is not resolved by toggling an optional security feature.

Details

The WebUI auth flow stores authorization state in session:

  • src/pyload/webui/app/helpers.py:187-200
  • set_session(...) writes:
  • "role": user_info["role"]
  • "perms": user_info["permission"]

Authorization checks later trust cached session values:

  • src/pyload/webui/app/helpers.py:134-151
  • parse_permissions(...) reads session.get("role") / session.get("perms")
  • src/pyload/webui/app/helpers.py:225-230
  • is_authenticated(...) only verifies authenticated and api.user_exists(user) (existence), not fresh role/permission
  • src/pyload/webui/app/helpers.py:267-275
  • login_required(...) uses parse_permissions(s) for allow/deny decisions
  • src/pyload/webui/app/helpers.py:356-365
  • API session auth path also trusts s["role"] and s["perms"]

Role/permission updates are written to DB but active sessions are not invalidated/refreshed:

  • src/pyload/webui/app/blueprints/json_blueprint.py:389-434
  • update_users(...) calls api.set_user_permission(...) and returns
  • src/pyload/core/api/__init__.py:1643-1645
  • set_user_permission(...) updates DB role/permission only

Default exposure window is long:

  • src/pyload/core/config/default.cfg:47
  • session_lifetime = 44640 minutes (~31 days)

Therefore, privilege revocation is not enforced immediately for active sessions.

Note on duplicates:

  • This appears distinct from CVE-2023-0227 (session validity after user deletion) because this report is about stale authorization after role/permission changes while the user still exists.

PoC

```python

#!/usr/bin/env python3

"""

Repro: stale session privilege after role/permission changes.

This PoC is source-based and leaves no persistent state.

It validates that:

1) Role/permission are cached into session at login.

2) Authorization checks read role/permission from session, not fresh DB values.

3) User updates write DB permission/role without invalidating active sessions.

4) Default session lifetime is long, increasing stale-privilege exposure window.

"""

from __future__ import annotations

import pathlib

import re

from typing import Iterable

ROOT = pathlib.Path(__file__).resolve().parent / "pyload" / "src" / "pyload"

def read(rel: str) -> str:

return (ROOT / rel).read_text(encoding="utf-8")

def has_any(text: str, patterns: Iterable[str]) -> bool:

return all(re.search(p, text, re.MULTILINE) for p in patterns)

def main() -> None:

helpers = read("webui/app/helpers.py")

json_blueprint = read("webui/app/blueprints/json_blueprint.py")

api_init = read("core/api/__init__.py")

default_cfg = (ROOT / "core/config/default.cfg").read_text(encoding="utf-8")

checks = {

"set_session_caches_role_perms": has_any(

helpers,

[

r'def\\s+set_session\\(',

r'"role"\\s*:\\s*user_info\\["role"\\]',

r'"perms"\\s*:\\s*user_info\\["permission"\\]',

],

),

"is_authenticated_only_checks_user_exists": has_any(

helpers,

[

r'def\\s+is_authenticated\\(',

r'api\\s*=\\s*flask\\.current_app\\.config\\["PYLOAD_API"\\]',

r'return\\s+authenticated\\s+and\\s+api\\.user_exists\\(user\\)',

],

),

"parse_permissions_reads_session_cache": has_any(

helpers,

[

r'def\\s+parse_permissions\\(',

r'session\\.get\\("role"\\)\\s*==\\s*Role\\.ADMIN',

r'session\\.get\\("perms"\\)',

],

),

"login_required_uses_parse_permissions_session": has_any(

helpers,

[

r'def\\s+login_required\\(',

r'if\\s+is_authenticated\\(s\\):',

r'perms\\s*=\\s*parse_permissions\\(s\\)',

],

),

"api_session_auth_uses_cached_role_perms": has_any(

helpers,

[

r'if\\s+is_authenticated\\(s\\):',

r'"role"\\s*:\\s*s\\["role"\\]',

r'"permission"\\s*:\\s*s\\["perms"\\]',

],

),

"update_users_changes_db_without_session_invalidation": has_any(

json_blueprint,

[

r'def\\s+update_users\\(',

r'api\\.set_user_permission\\(name,\\s*data\\["permission"\\],\\s*data\\["role"\\]\\)',

r'retu

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-41133 is classified as CWE-613: Insufficient Session Expiration. Sessions stay valid longer than they should, so an old identifier still grants access.

Affected software

CVE-2026-41133 is recorded against 2 packages.

  • pyload (fixed in 2026-04-13)
  • pyload-ng

Timeline and source

Published on 22 April 2026 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com

Other advisories for this package

pyload has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-613: Insufficient Session Expiration) in other software:

Details

Severity HIGH
CVSS Score 8.8
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE CWE-613
Public Exploit ⚠️ Yes
Source NVD
Published 2026-04-22
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
pyload 2026-04-13
pyload-ng

Similar Threats

Exploit Protection

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