pyload-ng CVE-2026-42312

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 option ("general", "ssl_verify") is not on that allowlist. Any authenticated user with the non-admin SETTINGS permission can set general.ssl_verify = off, and every subsequent outbound pycurl request is made with SSL_VERIFYPEER=0 and SSL_VERIFYHOST=0 - TLS peer and hostname verification are fully disabled. An on-path attacker can then present forged certificates for any hostname pyload fetches.

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.

Details

Writer - src/pyload/core/api/__init__.py, set_config_value() (around lines 215-290). The function is decorated with @permission(Perms.SETTINGS) and only rejects writes when (category, option) appears in ADMIN_ONLY_CORE_OPTIONS:

ADMIN_ONLY_CORE_OPTIONS = {
    ("general", "storage_folder"),
    ("log", "syslog_host"), ("log", "syslog_port"),
    ("proxy", "password"), ("proxy", "username"),
    ("reconnect", "script"),
    ("webui", "host"),
    ("webui", "ssl_certfile"), ("webui", "ssl_keyfile"), ("webui", "ssl_certchain"),
    ("webui", "use_ssl"),
}
...
if (category, option) in ADMIN_ONLY_CORE_OPTIONS and not is_admin:
    self.pyload.log.error(...); return
self.pyload.config.set(category, option, value)

("general", "ssl_verify") is absent. config.set() in src/pyload/core/config/parser.py:329 calls cast() which has no branch for enum-string types - "off" is stored verbatim and persisted to disk via self.save().

Reader - src/pyload/core/network/request_factory.py:109-110:

def get_options(self):
    return {
        "interface": self.iface(),
        "proxies":   self.get_proxies(),
        "ipv6":      self.pyload.config.get("download", "ipv6"),
        "ssl_verify": self.pyload.config.get("general", "ssl_verify"),
        ...
    }

Sink - src/pyload/core/network/http/http_request.py:193-206:

if "ssl_verify" in options:
    aiachaser_on = b"on (using aia-chaser)"
    if options["ssl_verify"] in [True, b"on", aiachaser_on]:
        ...
        ssl_verify = 1
    else:
        ssl_verify = 0
    self.c.setopt(pycurl.SSL_VERIFYPEER, ssl_verify)
    self.c.setopt(pycurl.SSL_VERIFYHOST, ssl_verify * 2)

Because get_options() is invoked every time a new pycurl handle is built, the new config value takes effect on the very next outbound request - no pyload restart required.

PoC

Authenticated as any user who has Perms.SETTINGS but is not admin (e.g. a user with Role.USER + the SETTINGS permission bit):

# 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) Disable TLS verification for all outbound downloads.
curl -b cookies.txt -X POST http://pyload.example:8000/api/setConfigValue \
    -d 'category=general&option=ssl_verify&value=off&section=core'
# -> 200 OK. Config persisted.
# 3) Enqueue any HTTPS download. An on-path attacker (shared LAN,
#    compromised upstream router, DNS hijack, or a malicious proxy
#    enabled via the sibling advisory on the proxy.* options) can
#    now present a forged cert for any target - pyload accepts it.

Verification: observe pycurl SSL_VERIFYPEER=0 in a debug build, or confirm that a download from an HTTPS endpoint served with a self-signed / mismatched cert succeeds after step 2 and fails before it.

Impact

• Who: any authenticated user whose role was granted Perms.SETTINGS. In multi-user pyload deployments that delegate settings administration to non-admins, this is an unintended privilege escalation from "can change UI/download settings" to "can silently disable TLS cert validation for all outbound fetches".
• What:

1. Man-in-the-middle on all HTTPS downloads, captcha fetches, update checks, and plugin HTTP calls.
2. Extends the impact of the already-published SSRF chain (CVE-2026-33992 / CVE-2026-35459). The URL-hostname validation those patches added is only meaningful if the TLS channel authenticates the endpoint; with ssl_verify=off, an on-path attacker can present forged certs for already-validated hosts - so HTTPS cloud-metadata endpoints and internal HTTPS services behind the host allowlist become reachable again.
3. Silent to the admin. Every adjacent security-critical option (proxy.password, SSL certfile/keyfile/certchain, use_ssl) is already admin-only, so the admin's mental model is that TLS policy cannot be weakened by a non-admin.

• Not impacted: unauthenticated attackers; users holding only DOWNLOAD / LIST roles.