Buffer Overflow vulnerability in giflib v.5.2.2 allows a remote attacker to cause a denial of service via the EGifGCBToExtension overwriting an existing Graphic Control Extension block without validating its allocated size.

Giflib contains a double-free vulnerability that is the result of a shallow copy in GifMakeSavedImage and incorrect error handling. The conditions needed to trigger this vulnerability are difficult but may be possible.