Leeds went into the match looking to extend their eight-game winning run in the league but could not claim their first ever win at Roots Hall, although they had the consolation of going a point clear of Charlton at the top of the table.
And Leeds had goalkeeper Shane Higgs to thank for the stalemate after he saved a Lee Barnard penalty midway through the second half.
Leeds enjoyed the better chances early on with fit-again striker Jermaine Beckford, Robert Snodgrass and Patrick Kisnorbo all having opportunities off target.
But Higgs had to block a sliding Jean-Francis effort and then parry Francis Laurent's powerful shot before Franck Moussa fired over with the goal at his mercy.
Beckford could have snatched the points at the death but his close-range shot was saved by Steve Mildenhall.