On January 9, Canonical published in a security notice details about a GnuPG vulnerability for its Ubuntu 12.10, Ubuntu 12.04 LTS, Ubuntu 11.10, Ubuntu 10.04 LTS, and Ubuntu 8.04 LTS operating systems.
According to Canonical, GNU privacy guard could have been made to corrupt the keyring if it imported a specially crafted key.
It was discovered that GnuPG incorrectly handled certain malformed keys. If a user or automated system were tricked into importing a malformed key, the GnuPG keyring could become corrupted.
For a more detailed description of the security problems, you can visit Canonical's security notification.
Users can simply fix the security flaws by upgrading the operating systems to the latest gnupg2 and gnupg packages specific to each distribution.
A normal system update, executed with the Update Manager, will implement all the necessary changes. A complete system restart is not necessary.