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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.1145 Multiple vulnerabilities in Ruby 6 April 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Ruby Publisher: Ruby Operating System: UNIX variants (UNIX, Linux, OSX) Windows Impact/Access: Create Arbitrary Files -- Remote/Unauthenticated Reduced Security -- Remote with User Interaction Resolution: Patch/Upgrade CVE Names: CVE-2021-28966 CVE-2021-28965 Reference: ESB-2019.2958 ESB-2019.2542 ESB-2018.3717 Original Bulletin: https://www.ruby-lang.org/en/news/2021/04/05/xml-round-trip-vulnerability-in-rexml-cve-2021-28965/ https://www.ruby-lang.org/en/news/2021/04/05/tempfile-path-traversal-on-windows-cve-2021-28966/ Comment: This bulletin contains two (2) Ruby security advisories. - --------------------------BEGIN INCLUDED TEXT-------------------- CVE-2021-28965: XML round-trip vulnerability in REXML Posted by mame on 5 Apr 2021 There is an XML round-trip vulnerability in REXML gem bundled with Ruby. This vulnerability has been assigned the CVE identifier CVE-2021-28965 . We strongly recommend upgrading the REXML gem. Details When parsing and serializing a crafted XML document, REXML gem (including the one bundled with Ruby) can create a wrong XML document whose structure is different from the original one. The impact of this issue highly depends on context, but it may lead to a vulnerability in some programs that are using REXML. Please update REXML gem to version 3.2.5 or later. If you are using Ruby 2.6 or later: o Please use Ruby 2.6.7, 2.7.3, or 3.0.1. o Alternatively, you can use gem update rexml to update it. If you are using bundler, please add gem "rexml", ">= 3.2.5" to your Gemfile . If you are using Ruby 2.5.8 or prior: o Please use Ruby 2.5.9. o You cannot use gem update rexml for Ruby 2.5.8 or prior. o Note that Ruby 2.5 series is now EOL, so please consider upgrading Ruby to 2.6.7 or later as soon as possible. Affected versions o Ruby 2.5.8 or prior (You can NOT use gem upgrade rexml for this version.) o Ruby 2.6.7 or prior o Ruby 2.7.2 or prior o Ruby 3.0.1 or prior o REXML gem 3.2.4 or prior Credits Thanks to Juho Nurminen for discovering this issue. History o Originally published at 2021-04-05 12:00:00 (UTC) - -------------------------------------------------------------------------------- CVE-2021-28966: Path traversal in Tempfile on Windows Posted by mame on 5 Apr 2021 There is an unintentional directory creation vulnerability in tmpdir library bundled with Ruby on Windows. And there is also an unintentional file creation vulnerability in tempfile library bundled with Ruby on Windows, because it uses tmpdir internally. This vulnerability has been assigned the CVE identifier CVE-2021-28966 . Details Dir.mktmpdir method introduced by tmpdir library accepts the prefix and the suffix of the directory which is created as the first parameter. The prefix can contain relative directory specifiers "..\\" , so this method can be used to target any directory. So, if a script accepts an external input as the prefix, and the targeted directory has inappropriate permissions or the ruby process has inappropriate privileges, the attacker can create a directory or a file at any directory. This is the same issue as CVE-2018-6914 , but the previous fix was incomplete on Windows. All users running an affected release should upgrade immediately. Affected versions o Ruby 2.7.2 or prior o Ruby 3.0.0 Credits Thanks to Bugdiscloseguys for discovering this issue. History o Originally published at 2021-04-05 12:00:00 (UTC) - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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