[3.9] bpo-43285 Make ftplib not trust the PASV response. (GH-24838) - #24880
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miss-islington merged 1 commit intoMar 15, 2021
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[3.9] bpo-43285 Make ftplib not trust the PASV response. (GH-24838)#24880miss-islington merged 1 commit into
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bpo-43285: Make ftplib not trust the PASV response. The IPv4 address value returned from the server in response to the PASV command should not be trusted. This prevents a malicious FTP server from using the response to probe IPv4 address and port combinations on the client network. Instead of using the returned address, we use the IP address we're already connected to. This is the strategy other ftp clients adopted, and matches the only strategy available for the modern IPv6 EPSV command where the server response must return a port number and nothing else. For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address` attribute on your `ftplib.FTP` instance to True. (cherry picked from commit 0ab152c) Co-authored-by: Gregory P. Smith <greg@krypto.org>
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bpo-43285: Make ftplib not trust the PASV response.
The IPv4 address value returned from the server in response to the PASV command
should not be trusted. This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.
Instead of using the returned address, we use the IP address we're
already connected to. This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.
For the rare user who wants this ugly behavior, set a trust_server_pasv_ipv4_address
attribute on your ftplib.FTP instance to True.
(cherry picked from commit 0ab152c)
Co-authored-by: Gregory P. Smith greg@krypto.org
https://bugs.python.org/issue43285
Automerge-Triggered-By: GH:gpshead