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Bug 828884 (CVE-2021-43809) - <dev-ruby/bundler-2.2.33: unexpected code execution in Gemfiles (CVE-2021-43809)
Summary: <dev-ruby/bundler-2.2.33: unexpected code execution in Gemfiles (CVE-2021-43809)
Status: IN_PROGRESS
Alias: CVE-2021-43809
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal normal (vote)
Assignee: Gentoo Security
URL: https://github.com/rubygems/rubygems/...
Whiteboard: B2 [glsa?]
Keywords:
Depends on: ruby30-stable
Blocks:
  Show dependency tree
 
Reported: 2021-12-11 05:05 UTC by John Helmert III
Modified: 2023-10-07 10:29 UTC (History)
1 user (show)

See Also:
Package list:
Runtime testing required: ---


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Description John Helmert III archtester Gentoo Infrastructure gentoo-dev Security 2021-12-11 05:05:24 UTC
CVE-2021-43809 (https://github.com/rubygems/rubygems/commit/a4f2f8ac17e6ce81c689527a8b6f14381060d95f):

`Bundler` is a package for managing application dependencies in Ruby. In `bundler` versions before 2.2.33, when working with untrusted and apparently harmless `Gemfile`'s, it is not expected that they lead to execution of external code, unless that's explicit in the ruby code inside the `Gemfile` itself. However, if the `Gemfile` includes `gem` entries that use the `git` option with invalid, but seemingly harmless, values with a leading dash, this can be false. To handle dependencies that come from a Git repository instead of a registry, Bundler uses various commands, such as `git clone`. These commands are being constructed using user input (e.g. the repository URL). When building the commands, Bundler versions before 2.2.33 correctly avoid Command Injection vulnerabilities by passing an array of arguments instead of a command string. However, there is the possibility that a user input starts with a dash (`-`) and is therefore treated as an optional argument instead of a positional one. This can lead to Code Execution because some of the commands have options that can be leveraged to run arbitrary executables. Since this value comes from the `Gemfile` file, it can contain any character, including a leading dash. To exploit this vulnerability, an attacker has to craft a directory containing a `Gemfile` file that declares a dependency that is located in a Git repository. This dependency has to have a Git URL in the form of `-u./payload`. This URL will be used to construct a Git clone command but will be interpreted as the upload-pack argument. Then this directory needs to be shared with the victim, who then needs to run a command that evaluates the Gemfile, such as `bundle lock`, inside. This vulnerability can lead to Arbitrary Code Execution, which could potentially lead to the takeover of the system. However, the exploitability is very low, because it requires a lot of user interaction. Bundler 2.2.33 has patched this problem by inserting `--` as an argument before any positional arguments to those Git commands that were affected by this issue. Regardless of whether users can upgrade or not, they should review any untrustred `Gemfile`'s before running any `bundler` commands that may read them, since they can contain arbitrary ruby code.


Please bump to 2.2.33.
Comment 1 John Helmert III archtester Gentoo Infrastructure gentoo-dev Security 2022-08-04 04:08:04 UTC
Please stabilize 2.2.33.
Comment 2 John Helmert III archtester Gentoo Infrastructure gentoo-dev Security 2022-09-27 01:14:20 UTC
Ping?
Comment 3 Hans de Graaff gentoo-dev Security 2023-10-07 10:29:25 UTC
commit 80e29b11359322de006f33edea77bc71314032bb
Author: Hans de Graaff <graaff@gentoo.org>
Date:   Sun Jul 2 07:18:55 2023 +0200

    dev-ruby/bundler: drop versions