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AUSCERT External Security Bulletin Redistribution
ESB-2021.2338
CVE-2021-31810: Trusting FTP PASV responses vulnerability in Net::FTP
8 July 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: Ruby
Publisher: Ruby
Operating System: UNIX variants (UNIX, Linux, OSX)
Windows
Impact/Access: Provide Misleading Information -- Unknown/Unspecified
Access Confidential Data -- Unknown/Unspecified
Resolution: Patch/Upgrade
CVE Names: CVE-2021-31810
Reference: ESB-2021.2337
Original Bulletin:
https://www.ruby-lang.org/en/news/2021/07/07/trusting-pasv-responses-in-net-ftp/
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CVE-2021-31810: Trusting FTP PASV responses vulnerability in Net::FTP
Posted by shugo on 7 Jul 2021
A trusting FTP PASV responses vulnerability was discovered in Net::FTP. This
vulnerability has been assigned the CVE identifier CVE-2021-31810 . We strongly
recommend upgrading Ruby.
net-ftp is a default gem in Ruby 3.0.1 but it has a packaging issue, so please
upgrade Ruby itself.
Details
A malicious FTP server can use the PASV response to trick Net::FTP into
connecting back to a given IP address and port. This potentially makes Net::FTP
extract information about services that are otherwise private and not disclosed
(e.g., the attacker can conduct port scans and service banner extractions).
Affected Versions
o Ruby 2.6 series: 2.6.7 and earlier
o Ruby 2.7 series: 2.7.3 and earlier
o Ruby 3.0 series: 3.0.1 and earlier
Credits
Thanks to Alexandr Savca for reporting the issue.
History
o Originally published at 2021-07-07 09:00:00 UTC
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