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[3.13] gh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (GH-149648)#149794

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May 13, 2026
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[3.13] gh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (GH-149648)#149794
gpshead merged 1 commit into
python:3.13from
miss-islington:backport-eac4fe3-3.13

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@miss-islington miss-islington commented May 13, 2026

ftpcp() called parse227() directly and passed the source server's
self-reported PASV IPv4 address to the target server's PORT command,
bypassing the CVE-2021-4189 fix that was applied only to FTP.makepasv().
A malicious source FTP server could use this to redirect the target
server's data connection to an arbitrary host:port (SSRF).

ftpcp() now uses the source server's actual peer address, honoring the
existing trust_server_pasv_ipv4_address opt-out, the same as makepasv().

Thanks to Qi Ding at Aurascape AI for the report. (GHSA-w8c5-q2xf-gf7c)
(cherry picked from commit eac4fe3)

Co-authored-by: Gregory P. Smith 68491+gpshead@users.noreply.github.com

…nGH-149648)

ftpcp() called parse227() directly and passed the source server's
self-reported PASV IPv4 address to the target server's PORT command,
bypassing the CVE-2021-4189 fix that was applied only to FTP.makepasv().
A malicious source FTP server could use this to redirect the target
server's data connection to an arbitrary host:port (SSRF).

ftpcp() now uses the source server's actual peer address, honoring the
existing trust_server_pasv_ipv4_address opt-out, the same as makepasv().

Thanks to Qi Ding at Aurascape AI for the report. (GHSA-w8c5-q2xf-gf7c)
(cherry picked from commit eac4fe3)

Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
@gpshead gpshead enabled auto-merge (squash) May 13, 2026 17:53
@gpshead gpshead merged commit bb3446d into python:3.13 May 13, 2026
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@miss-islington miss-islington deleted the backport-eac4fe3-3.13 branch May 13, 2026 17:58
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