CVE-2022-31163.yml

---
gem: tzinfo
cve: 2022-31163
ghsa: 5cm2-9h8c-rvfx
url: https://github.com/tzinfo/tzinfo/security/advisories/GHSA-5cm2-9h8c-rvfx
title: TZInfo relative path traversal vulnerability allows loading of arbitrary files
date: 2022-07-21
description: |
  # Impact

  ## Affected versions

  - 0.3.60 and earlier.
  - 1.0.0 to 1.2.9 when used with the Ruby data source (tzinfo-data).

  ## Vulnerability

  With the Ruby data source (the tzinfo-data gem for tzinfo version 1.0.0 and
  later and built-in to earlier versions), time zones are defined in Ruby files.
  There is one file per time zone. Time zone files are loaded with `require` on
  demand. In the affected versions, `TZInfo::Timezone.get` fails to validate
  time zone identifiers correctly, allowing a new line character within the
  identifier. With Ruby version 1.9.3 and later, `TZInfo::Timezone.get` can be
  made to load unintended files with `require`, executing them within the Ruby
  process.

  For example, with version 1.2.9, you can run the following to load a file with
  path `/tmp/payload.rb`:

  ```ruby
  TZInfo::Timezone.get(\"foo\
  /../../../../../../../../../../../../../../../../tmp/payload\")
  ```

  The exact number of parent directory traversals needed will vary depending on
  the location of the tzinfo-data gem.

  TZInfo versions 1.2.6 to 1.2.9 can be made to load files from outside of the
  Ruby load path. Versions up to and including 1.2.5 can only be made to load
  files from directories within the load path.

  This could be exploited in, for example, a Ruby on Rails application using
  tzinfo version 1.2.9, that allows file uploads and has a time zone selector
  that accepts arbitrary time zone identifiers.
  The CVSS score and severity have been set on this basis.

  Versions 2.0.0 and later are not vulnerable.

  # Patches

  Versions 0.3.61 and 1.2.10 include fixes to correctly validate time zone
  identifiers.

  Note that version 0.3.61 can still load arbitrary files from the Ruby load
  path if their name follows the rules for a valid time zone identifier and the
  file has a prefix of `tzinfo/definition` within a directory in the load path.
  For example if `/tmp/upload` was in the load path, then
  `TZInfo::Timezone.get('foo')` could load a file with path
  `/tmp/upload/tzinfo/definition/foo.rb`. Applications should ensure that
  untrusted files are not placed in a directory on the load path.

  # Workarounds

  As a workaround, the time zone identifier can be validated before passing to
  `TZInfo::Timezone.get` by ensuring it matches the regular expression
  `\\A[A-Za-z0-9+\\-_]+(?:\\/[A-Za-z0-9+\\-_]+)*\\z`.
cvss_v3: 7.5
unaffected_versions:
  - ">= 2.0.0"
patched_versions:
  - "~> 0.3.61"
  - ">= 1.2.10"
related:
  url:
    - https://github.com/tzinfo/tzinfo/commit/ca29f349856d62cb2b2edb3257d9ddd2f97b3c27
    - https://github.com/tzinfo/tzinfo/releases/tag/v0.3.61
    - https://github.com/tzinfo/tzinfo/releases/tag/v1.2.10