Everything is OK because there is cricket

On Day 5 of the Second Ashes Test, when England were desperate to keep the run-rate down, Kevin Pietersen chucked a wild one that missed the stumps, adding 4 overthrows to Langer's 3 score- for a total of 7 runs off one ball.

It didn't attract much comment, but it made me curious about historical one-ball high scores, so off to virtual Wisden. The highest I have found so far is 17 runs off one ball.

Deepak Shah explains on All Experts:

Normally maximum runs scored off one ball is 6. It could be more, if you are allowed by the fielding side to run more runs (I have scored 8 in a college game in Ahmedabad, India in 1972). However, under these circumstances (like the ball gets lost within the field as it happened in my game due to tall grass) the fielding side can declare "Lost Ball" and I think batting side and the batsman (if the ball is hit) will get 6 runs plus all that he has run. However, the question of 17 runs off one ball can be explained as follows:

If the bowler bowls more than one illegitimate delivery (no balls) before a legitimate ball is bowled, all the runs scored COLLECTIVELY, will count in the score book towards one ball. e.g. a bowler bowls 3 no balls and is hit for all fours (12 + 3 =15 runs). Next ball is legitimate and he concedes 2 runs. In the score book that goes as 17 off one LEGITIMATE delivery.

This happened in the first ODI between India-Pakistan in March 2004 at Karachi. Pakistani bowler Rana Naved-Ul-Hasan conceded 24 runs in his first over with 4 no balls. I think he bowled 3 or all 4 no balls consequtively and ended up with 17 off one ball.