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GeezerVison is showing github.com — [3.8] bpo-43285 Make ftplib not trust the PASV response. (GH-24838) by gpshead · Pull Request #24881 · python/cpython

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@gpshead

@gpshead gpshead commented Mar 15, 2021 •
edited by bedevere-bot
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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

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@gpshead
[3.8] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838
6433c5f
)

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]>
@gpshead gpshead added type-bug An unexpected behavior, bug, or error needs backport to 3.6 type-security A security issue labels Mar 15, 2021
@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 the awaiting core review label Mar 15, 2021
@gpshead gpshead self-assigned this Mar 15, 2021
@gpshead
gpshead merged commit 664d1d1 into python:3.8 Mar 15, 2021
@miss-islington

miss-islington commented Mar 15, 2021

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Thanks @gpshead for the PR 🌮🎉.. I'm working now to backport this PR to: 3.6, 3.7.
🐍🍒⛏🤖 I'm not a witch! I'm not a witch!

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@bedevere-bot bedevere-bot removed the awaiting core review label Mar 15, 2021
@miss-islington

miss-islington commented Mar 15, 2021

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Sorry @gpshead, I had trouble checking out the 3.7 backport branch.
Please backport using cherry_picker on command line.
cherry_picker 664d1d16274b47eea6ec92572e1ebf3939a6fa0c 3.7

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@bedevere-bot

bedevere-bot commented Mar 15, 2021

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GH-24882 is a backport of this pull request to the 3.6 branch.

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@bedevere-bot bedevere-bot removed the needs backport to 3.6 label Mar 15, 2021
@gpshead gpshead added needs backport to 3.7 and removed needs backport to 3.7 labels Mar 15, 2021
@miss-islington

miss-islington commented Mar 15, 2021

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Thanks @gpshead for the PR 🌮🎉.. I'm working now to backport this PR to: 3.7.
🐍🍒⛏🤖

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miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Mar 15, 2021
@gpshead @miss-islington
[3.8] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838
8759ca4
) (pythonGH-24881)

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]>
(cherry picked from commit 664d1d1)

Co-authored-by: Gregory P. Smith <[email protected]>
@bedevere-bot

bedevere-bot commented Mar 15, 2021

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GH-24883 is a backport of this pull request to the 3.7 branch.

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@bedevere-bot bedevere-bot removed the needs backport to 3.7 label Mar 15, 2021
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Mar 15, 2021
@gpshead @miss-islington
[3.8] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838
a27bc4f
) (pythonGH-24881)

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]>
(cherry picked from commit 664d1d1)

Co-authored-by: Gregory P. Smith <[email protected]>
ned-deily pushed a commit that referenced this pull request Mar 16, 2021
@miss-islington @gpshead
[3.6] bpo-43285 Make ftplib not trust the PASV response. (GH-24838) (G…
4134f15
…H-24881) (GH-24882)

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]>
(cherry picked from commit 664d1d1)
ned-deily pushed a commit that referenced this pull request Mar 16, 2021
@miss-islington @gpshead
[3.7] bpo-43285 Make ftplib not trust the PASV response. (GH-24838) (G…
7937395
…H-24881) (GH-24883)

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]>
(cherry picked from commit 664d1d1)
gentoo-bot pushed a commit to gentoo/cpython that referenced this pull request Apr 3, 2021
@miss-islington @mgorny
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838
fe31479
) (pythonGH-24881) (pythonGH-24882)

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]>
(cherry picked from commit 664d1d1)

Rebased for Python 2.7 by Michał Górny <[email protected]>
@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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