In addition to adding the higher-level Ultimate Vault Hunter difficulty mode, the latest update for Borderlands 2 on Steam adds new item upgrades and fixes a number of bugs in specific missions, according to the patch notes.
New items have been added to the game's Black Market, including an additional ammo upgrade for each ammo type, two upgrades for backpack storage space and two more bank storage upgrades. A number of weapons exploits granting players infinite ammo or invulnerability have also been rectified.
In the Mr. Torgue Campaign of Carnage DLC, Rat Thief enemy types have been removed from the Pete's Bar area and critical hits against Midget enemies will now register properly. The Thermitage mini-boss has also been tweaked to be more "friendly," as a previous bug would occasionally prevent him from engaging with players. Bugs preventing players from completing certain challenges in the the Captain Scarlett and Her Pirate's Booty DLC have also been fixed. Seraph Gear available in both missions have also been re-balanced to be more powerful.
The full list of patch notes is available on Steam.