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2.7.18.16: ftplib.ftpcp() trusts the PASV host (CVE-2026-8328) - #94
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…026-8328) Backport of python/cpython pythongh-87451 (3.15 5dadc64). 2.7.18.x already carries the CVE-2021-4189 fix in FTP.makepasv(): it ignores the IPv4 address a server advertises in its PASV reply and uses the control connection's peer address unless trust_server_pasv_ipv4_address is set. ftpcp() still called parse227() directly and passed the server-supplied host to target.sendport(), so a malicious source server could point the target's data connection at an arbitrary host:port (SSRF). ftpcp() now applies the same rule. 2.7.18.x: no unittest.mock in 2.7, so TestFtpcpSecurity uses small fake FTP/socket classes; % formatting instead of f-strings; the class is added to test_main(). Co-Authored-By: Claude Opus 5.5 <[email protected]>
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No blockers.
- Fix matches upstream. The new
ftpcp()code is line-for-line upstream pythongh-87451 (eac4fe3). There are no later upstream changes toftpcp(). - Repro: a source server whose PASV reply advertises
10.0.0.99while its real peer address is203.0.113.5:- Base:
target.sendport('10.0.0.99', 1930). - This branch:
target.sendport('203.0.113.5', 1930).
- Base:
- Tests:
test_ftplibon this branch: 85 run. The 2 failures and 1 error (test_source_address,test_source_address_passive_connection,test_with_statement) are identical on the base, which runs 83.
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Backport of python/cpython pythongh-87451 (CVE-2026-8328, PSF-2026-24) to 2.7.18.x.
Problem: 2.7.18.x already has the CVE-2021-4189 fix in
FTP.makepasv(), butftpcp()still passed the host from the source server's PASV reply straight totarget.sendport(). A malicious source server could therefore redirect the target's data connection to any host:port (SSRF).Fix:
ftpcp()now follows the same rule asmakepasv(). It uses the source's real peer address unlesstrust_server_pasv_ipv4_addressis set.Test:
TestFtpcpSecurity. Python 2.7 has nounittest.mock, so the test uses small fake FTP objects.test_ftpcp_ignores_untrusted_pasv_hostfails on 2.7.18.15 and passes with the fix. The other 6test_ftplibfailures are the existing source-address and with-statement failures from my local environment, and they happen with or without this change.Part of 2.7.18.16. It targets the
2.7.18.16integration branch.