Leaks

Leaks are information about future updates planned for RuneScape that are accidentally/secretively (meaning, not as Chaos Elemental Letters or Behind the Scenes articles) posted on any part of the RuneScape website that discloses information that was not intended to be released to the public as of that moment. If it was posted in the Knowledge Base, it is commonly known as a KB leak, and it happens when Jagex Staff posts information into the Knowledge Base too early.

Known Leaks
Legend: IG=In-game KB=Knowledge Base WS=Website Leak

Unreleased leaks

 * (IG) Before the Rocking Out quest came out, when a player would reach a thieving level of 63. On the thieving Level up screen, a message would say that " You can now steal from Custom Officer's Tables".
 * (IG) Soul rune crafting (Level 90 Runecrafting Level up screen shows you can craft Soul Runes)
 * (WS) At one point, a very large area of land was visible across the ocean west of Tirannwn on the world map. It appeared very pixelated and unrefined. It was removed shortly after.
 * (WS) On the RuneScape homepage, there was a picture of a man holding a magical staff in a boat. The man is also wearing a Skill Cape with an icon that doesn't identify to any of the 24 skills. Rumours say that this is a Sailing Skill Cape for a future Sailing skill. There is also some minor evidence that also leads to this like the addition water on the world map, and the temporary Sailing stat bug on the RuneScape highscores. However, in light of moderator confirmation of all sailing skill cape claims being false, and that no such skill was in the works, it seems unlikely that this skill is at any point of development at this time.
 * (WS) On the RuneScape homepage, there was a picture of a woman wearing an unknown piece of red chest armour. Many people believe that it is the dragon platebody. There is also a concept design of the rumoured dragon platebody on the Jagex website, viewable here. The platebody was released with the While Guthix Sleeps quest.
 * (IG) As of yet, the Trade Octagon serves no purpose to players. There was a leak in which a mini-game icon was put on the mini-map in the Trade Octagon. It was quickly removed, but a Jagex Moderator confirmed that there was a mini-game planned for the area. Whether or not the mini-game is still being made is unknown, as the moderator said it kept getting pushed to the bottom of his pile of work.