Fix for: Prior to 0.1.6, libyaml is vulnerable to a heap overflow exploit from malicious YAML payloads

Question

I get the following error when running rspec after I added the vcr gem. Simply running gem install psych -- --enable-bundled-libyaml as suggested doesn't solve the problem. I am using rbenv and ruby-build and I am on ruby 2.1.1. What do i have to do to fix this?

SafeYAML Warning
  ----------------

  You appear to have an outdated version of libyaml (0.1.4) installed on your system.

  Prior to 0.1.6, libyaml is vulnerable to a heap overflow exploit from malicious YAML payloads.

  For more info, see:
  https://www.ruby-lang.org/en/news/2014/03/29/heap-overflow-in-yaml-uri-escape-parsing-cve-2014-2525/

  The easiest thing to do right now is probably to update Psych to the latest version and enable
  the 'bundled-libyaml' option, which will install a vendored libyaml with the vulnerability patched:

  gem install psych -- --enable-bundled-libyaml

Answer 1

First, you have to update Ruby-build, they have recently patched this security issue. Now, it installs libyaml 0.1.6 to compile Ruby.

$ rm -rf ~/.rbenv/plugins/ruby-build
$ git clone https://github.com/sstephenson/ruby-build.git ~/.rbenv/plugins/ruby-build

Recompile, reinstall the Ruby version you are using, 2.0.0-p451 in my case:

$ rbenv install 2.0.0-p451
rbenv: /home/ubuntu/.rbenv/versions/2.0.0-p451 already exists
continue with installation? (y/N) y
Downloading yaml-0.1.6.tar.gz...
-> http://dqw8nmjcqpjn7.cloudfront.net/5fe00cda18ca5daeb43762b80c38e06e
...

And it worked in my case.

Answer 2

I just followed the instructions in this reply https://stackoverflow.com/a/9510209/816002 and it seems to have done the trick. I did it slightly different however:

rvm pkg install libyaml
rvm get stable
rvm reinstall all --force

This might not help if you are using system Ruby, and will obviously be different with rbenv.

Answer 3

As a user of rvm, I managed to get my set up to play ball by building 0.1.6 release of libyaml, then (re)installing Ruby, passing the following configure flag

rvm install 1.9.3 -- --with-libyaml-dir=/usr/local

Hope this helps people in the short-term until the dust settles.

Answer 4

If you're on Mac OS X / Mavericks then you may be running on the system-installed Ruby. Thoughbot encourages you not to do this. I was having this problem as well, so I followed their advice and installed brew and rbenv and the problem went away.

Answer 5

For rvm this worked for me:

rvm pkg install libyaml
$LIBYAML_PATH will be the path where RVM installs the upated yaml
rvm get stable
rvm reinstall all --force --with-libyaml-dir=$LIBYAML_PATH

http://synaptian.com/2014/04/fixing-the-safeyaml-warning-on-ubuntu-12-04-with-rvm/