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GeezerVison is showing github.com — [3.10] gh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (GH-149648) by miss-islington · Pull Request #149797 · python/cpython

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@miss-islington

@miss-islington miss-islington commented May 13, 2026 •
edited by bedevere-app Bot
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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 [email protected]

  • Issue: ftplib should not use the host from the PASV response #87451

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@gpshead @miss-islington
pythongh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (pytho…
6b799df 
…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 <[email protected]>
This was referenced May 13, 2026
ftplib should not use the host from the PASV response #87451
Closed
gh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() #149648
Merged
@bedevere-app bedevere-app Bot added type-security A security issue awaiting review labels May 13, 2026
@gpshead gpshead added the release-blocker label May 13, 2026
@github-project-automation github-project-automation Bot added this to Release and Deferred blockers 🚫 May 13, 2026
@github-project-automation github-project-automation Bot moved this to Todo in Release and Deferred blockers 🚫 May 13, 2026
@gpshead gpshead assigned pablogsal May 13, 2026
@pablogsal
pablogsal merged commit 2bbcf3f into python:3.10 Jun 27, 2026
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@bedevere-app bedevere-app Bot removed the awaiting review label Jun 27, 2026
@github-project-automation github-project-automation Bot moved this from Todo to Done in Release and Deferred blockers 🚫 Jun 27, 2026
@miss-islington
miss-islington deleted the backport-eac4fe3-3.10 branch June 27, 2026 17:58
icanhasmath pushed a commit to ActiveState/cpython that referenced this pull request Oct 28, 2026
@miss-islington @gpshead @icanhasmath
[3.10] pythongh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (…
7ff917f 
…pythonGH-149648) (python#149797)

pythongh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (pythonGH-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 <[email protected]>
(cherry picked from commit 2bbcf3f)
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@miss-islington @gpshead @pablogsal
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