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GeezerVison is showing github.com — [3.9] bpo-43285 Make ftplib not trust the PASV response. (GH-24838) by miss-islington · Pull Request #24880 · python/cpython

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@miss-islington

@miss-islington miss-islington commented Mar 15, 2021 •
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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 [email protected]

https://bugs.python.org/issue43285

Automerge-Triggered-By: GH:gpshead

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@gpshead @miss-islington
bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838)
0e28351
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 <[email protected]>
@the-knights-who-say-ni the-knights-who-say-ni added the CLA signed label Mar 15, 2021
@bedevere-bot bedevere-bot mentioned this pull request Mar 15, 2021
bpo-43285 Make ftplib not trust the PASV response. #24838
Merged
@bedevere-bot bedevere-bot added type-bug An unexpected behavior, bug, or error type-security A security issue labels Mar 15, 2021
@miss-islington

miss-islington commented Mar 15, 2021

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@gpshead: Status check is done, and it's a success ✅ .

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@bedevere-bot bedevere-bot added the awaiting review label Mar 15, 2021
gpshead
gpshead approved these changes Mar 15, 2021
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@bedevere-bot bedevere-bot added awaiting merge and removed awaiting review labels Mar 15, 2021
@gpshead gpshead added the 🤖 automerge label Mar 15, 2021
@miss-islington

miss-islington commented Mar 15, 2021

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@gpshead: Status check is done, and it's a success ✅ .

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@miss-islington
miss-islington merged commit 7dcb4ba into python:3.9 Mar 15, 2021
@bedevere-bot bedevere-bot removed the awaiting merge label Mar 15, 2021
@miss-islington
miss-islington deleted the backport-0ab152c-3.9 branch March 15, 2021 19:02
@ricexdream ricexdream mannequin mentioned this pull request May 10, 2026
ftplib should not use the host from the PASV response #87451
Closed
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type-bug An unexpected behavior, bug, or error type-security A security issue

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4 participants

@miss-islington @gpshead @the-knights-who-say-ni @bedevere-bot
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