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GeezerVison is showing github.com — [3.12] gh-87451: Apply CVE-2021-4189 PASV fix to ftplib.ftpcp() (GH-149648) by miss-islington · Pull Request #149795 · 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…
b026be6
…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
@read-the-docs-community

read-the-docs-community Bot commented May 13, 2026

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Documentation build overview

📚 cpython-previews | 🛠️ Build #32677385 | 📁 Comparing b026be6 against main (94bca40)

  🔍 Preview build  

533 files changed · + 3 added · ± 477 modified · - 53 deleted

+ Added

  • c-api/objbuffer.html
  • library/2to3.html
  • library/tkinter.tix.html

± Modified

  • about.html
  • bugs.html
  • copyright.html
  • glossary.html
  • index.html
  • license.html
  • py-modindex.html
  • c-api/abstract.html
  • c-api/allocation.html
  • c-api/apiabiversion.html
  • and 467 more...

- Deleted

  • 404.html
  • improve-page-nojs.html
  • improve-page.html
  • _static/tachyon-example-flamegraph.html
  • _static/tachyon-example-heatmap.html
  • c-api/curses.html
  • c-api/extension-modules.html
  • c-api/interp-lifecycle.html
  • c-api/lifecycle.html
  • c-api/monitoring.html
  • and 43 more...
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@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 Yhg1s May 13, 2026
@Yhg1s
Yhg1s merged commit c887044 into python:3.12 May 18, 2026
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@bedevere-app bedevere-app Bot removed the awaiting review label May 18, 2026
@github-project-automation github-project-automation Bot moved this from Todo to Done in Release and Deferred blockers 🚫 May 18, 2026
@miss-islington
miss-islington deleted the backport-eac4fe3-3.12 branch May 18, 2026 17:59
@UTsweetyfish UTsweetyfish mentioned this pull request May 21, 2026
python3.12: CVE-2026-4519, CVE-2026-3644, CVE-2026-4224, ... deepin-community/sig-deepin-security#330
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@miss-islington @gpshead @Yhg1s
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