The good. Some things to keep you safe(r), if you use GnuPG:

saneprefs contains a reasonably sane set of preferences for GnuPG.

safeimport contains utilities for safely importing keys from keyservers:

• import_by_fingerprint.py is a small Python script that executes the necessary steps to safely import a PGP key from a keyserver. It is based on Michael Vogt's script used by the apt-add-repository utility in Ubuntu. Suitable for use in automated contexts.

• recvkey.sh is a simple shell script that is fairly safe; it's CC0 licensed.

(To set up GnuPG to import keys over https, see https://sks-keyservers.net/overview-of-pools.php; but note that the requirements to obtain an SKS keyserver certificate are very weak. It is insufficient to rely on this for safety.)

The bad. Some exotic testcases for software implementing the OpenPGP standard.

pgpv4 contains PGPv4 keys with colliding key ids.

The ugly. Various attacks on OpenPGP implementations. (These are attacks at the protocol level; not exploits.)

keysteak is a proof-of-concept keyserver-in-the-middle which uses the old 0xdeadbeef attack. Check whether it works on your OpenPGP implementation of choice. Just when you thought you were safe. . . .

encrux provides some PoC code for a downgrade attack that uses an integrity-protected message to get a valid non-integrity-protected message (with p=2^-15).

discus will contain a fully "weaponized" double-share-key-share attack on RSA signatures.

See the individual directories / scripts. In brief,

• pgpv4: CC0
• safeimport/import_by_fingerprint.py: GPL2 (my changes under CC0)
• keysteak: AGPL3
• discus: AGPL3
• encrux: AGPL3