USN-2461-3: PyYAML vulnerability

12 January 2015

pyyaml vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 14.10
  • Ubuntu 14.04 LTS
  • Ubuntu 12.04 LTS


Applications using PyYAML could be made to crash if they received specially crafted input.

Software Description

  • pyyaml - YAML parser and emitter for Python


Stanisław Pitucha and Jonathan Gray discovered that PyYAML did not properly handle wrapped strings. An attacker could create specially crafted YAML data to trigger an assert, causing a denial of service.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 14.10
python-yaml - 3.11-1ubuntu0.1
python3-yaml - 3.11-1ubuntu0.1
Ubuntu 14.04 LTS
python-yaml - 3.10-4ubuntu0.1
python3-yaml - 3.10-4ubuntu0.1
Ubuntu 12.04 LTS
python-yaml - 3.10-2ubuntu0.1
python3-yaml - 3.10-2ubuntu0.1

To update your system, please follow these instructions:

After a standard system update you need to restart applications using PyYAML to make all the necessary changes.