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GeezerVison is showing github.com — bpo-43285 Make ftplib not trust the PASV response. by gpshead · Pull Request #24838 · python/cpython

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@gpshead

@gpshead gpshead commented Mar 13, 2021 •
edited by bedevere-bot
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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.

https://bugs.python.org/issue43285

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@gpshead
bpo-43285 Make ftplib not trust the PASV response.
4b397c1
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.
@gpshead gpshead added type-bug An unexpected behavior, bug, or error needs backport to 3.6 type-security A security issue labels Mar 13, 2021
@the-knights-who-say-ni the-knights-who-say-ni added the CLA signed label Mar 13, 2021
@bedevere-bot bedevere-bot added the awaiting core review label Mar 13, 2021
@gpshead
gpshead requested a review from vstinner March 13, 2021 11:56
vstinner
vstinner reviewed Mar 13, 2021
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Comment thread Lib/ftplib.py Resolved

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@gpshead
Rename the legacy behavior attribute and mention it in NEWS.
6003e2f
`trust_server_pasv_ipv4_address`
@gpshead gpshead self-assigned this Mar 13, 2021
@gpshead
gpshead merged commit 0ab152c into python:master 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, 3.8, 3.9.
🐍🍒⛏🤖

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@bedevere-bot bedevere-bot removed the awaiting core review label Mar 15, 2021
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Mar 15, 2021
@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]>
@bedevere-bot bedevere-bot removed the needs backport to 3.9 label Mar 15, 2021
@bedevere-bot

bedevere-bot commented Mar 15, 2021

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GH-24880 is a backport of this pull request to the 3.9 branch.

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@miss-islington

miss-islington commented Mar 15, 2021

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Sorry, @gpshead, I could not cleanly backport this to 3.8 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 0ab152c6b5d95caa2dc1a30fa96e10258b5f188e 3.8

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@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 0ab152c6b5d95caa2dc1a30fa96e10258b5f188e 3.7

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@miss-islington

miss-islington commented Mar 15, 2021

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Sorry, @gpshead, I could not cleanly backport this to 3.6 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 0ab152c6b5d95caa2dc1a30fa96e10258b5f188e 3.6

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gpshead added a commit to gpshead/cpython that referenced this pull request Mar 15, 2021
@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]>
@bedevere-bot bedevere-bot removed the needs backport to 3.8 label Mar 15, 2021
@bedevere-bot

bedevere-bot commented Mar 15, 2021

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GH-24881 is a backport of this pull request to the 3.8 branch.

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miss-islington added a commit that referenced this pull request Mar 15, 2021
@miss-islington @gpshead
bpo-43285 Make ftplib not trust the PASV response. (GH-24838)
7dcb4ba
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 added a commit that referenced this pull request Mar 15, 2021
@gpshead
[3.8] bpo-43285 Make ftplib not trust the PASV response. (GH-24838) (G…
664d1d1
…H-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]>
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]>
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]>
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 8, 2024
@rickprice @gpshead
CVE-2021-4180 cherry-pick Fix 4134f15
b903a48
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 8, 2024
@rickprice @gpshead
CVE-2021-4180 cherry-pick Fix 4134f15
36a17ec
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 13, 2024
@rickprice @gpshead
CVE-2021-4180 cherry-pick Fix 4134f15
235a201
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 13, 2024
@rickprice @gpshead
CVE-2021-4189 cherry-pick Fix 4134f15
73bb207
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
rickprice added a commit to ActiveState/cpython that referenced this pull request Jun 26, 2024
@rickprice @gpshead
CVE-2021-4189 cherry-pick Fix 4134f15
d72594e
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
icanhasmath pushed a commit to ActiveState/cpython that referenced this pull request Jul 30, 2024
@rickprice @gpshead @icanhasmath
CVE-2021-4189 cherry-pick Fix 4134f15
8ebb54f
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
icanhasmath pushed a commit to ActiveState/cpython that referenced this pull request Jul 30, 2024
@rickprice @gpshead @icanhasmath
CVE-2021-4189 cherry-pick Fix 4134f15
1a25963
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-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)
@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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