Boro failed to collect a record eighth successive clean sheet at home as they leaked a late leveller in a 1- draw with Forest.
Mustapha Carayol put them ahead early in the second half but Darius Henderson equalised just six minutes from time – the first goal the Teessiders had conceded in 11 hours and 54 minutes.
Boro pressed first in the opening minute as Emmanuel Ledesma got down the right to cross and Danny Graham glanced a header wide of the far post.
Forest's first probe came on seven minutes as a quick Cox ball over the top sent Majewski clear to scoot down the inside left channel but he screwed well wide from 20 yards.
Then another ball forward on 10 minutes sent Cox racing forward but Grant Leadbitter tracked him all the way and stretched to turn the shot behind for a corner which was headed wide by Lascelles.
Boro almost grabbed the opener on 14 minutes as the keeper fumbled an in-swinging corner from Leadbitter and when it squirted to the far post Mustapha Carayol nipped in to head it goalwards but alert Lascelles nodded off the line.
There was a scare on 20 minutes as Paterson crossed into a crowded box and as it bounced about it fell to Cox but he couldn't control and alert Varga bundled it away.
Then Forest had a good spell and Boro were forced into some anxious defending.
And the visitors almost got the opener on 32 minutes as Abdoun crossed in from the right for Cox six yards out and unmarked but his downward header was weak, although Dimi Konstantopoulos still had to be alert to go full length and smother on the line.
Increasingly dangerous Forest threatened again on 37 minutes as Abdoun cracked in a stinging 25 yards effort that again brought a good diving save from the keeper.
And soon after Majewski controlled well on the edge of the box and sent a shot screaming just wide.
But Boro broke out to threaten just before the break as Chalobah sent Carayol weaving forward to check inside his man on the edge of the box and rifle a low shot just wide.
Straight down the other end Forest went close as Majewski sent a low 25 yard effort skidding just wide.
Boro started the half on the offensive although their early possession was hurried and scrappy.
Forest carved out the first chance on 52 minutes as a Patterson free-kick from the left dipped to the far post where an attempted header by Leadbitter flashed backwards and bounced just outside the far post.
From the corner Boro cleared quickly to score the opener on 53 minutes.
After a scramble, the ball was played down the right for Albert Adomah to collect and carry forward then cut inside and square across the edge of the box towards the run of MUSTAPHA CARAYOL, who took a deft touch then curled it just inside the foot of the far post.
Forest had a good chance soon after as a good move took Cox into the box but Ben Gibson arrived with a good blocking tackle as he shaped to shoot then Mackie screwed the rebound well wide from 10 yards out.
Boro threatened again on the hour as Carayol collected a ball out of the box and twisted to create space then flicked down the left to send Friend over-lapping and cutting past his man to get into the box but his shot was blocked.
After a scrappy spell Boro broke out and almost got a second goal similar to the opener on 69 minutes.
Leadbitter picked out the run of Carayol down the inside left channel and again he checked neatly inside his man and curled a 15 yard shot towards the far post but this time it drifted a fraction wide.
And two minutes later Carayol surged forward again onto a Chalobah ball and cut into the box but this time his shot was blocked by defender Jara.
Forest levelled out of the blue on 80 minutes as Reid got down the left and sent a cross skidding into the box for unmarked DARIUS HENDERSON to stab goalwards and when keeper Konstantopoulos blocked he bundled home the rebound with Boro fans screaming for handball.
Boro were almost back in front within three minutes as Kamara nodded on a Friend free-kick and after a scramble the ball fell to Graham six yards out but his stabbed effort cannoned off the post and was scrambled away.
Then on 86 minutes Boro had a golden chance as Graham chested down a ball into the box but he dithered giving Jara the chance to get back and pressure him and his shot, when it came, screwed well wide of the target from 12 yards.
BORO : Konstantopoulos, Varga, Gibson, Omeruo, Friend, Chalobah, Leadbitter (c), Ledesma (Whitehead 62), Tomlin (Adomah 36), Carayol, Graham. Subs: Steele, Kamara, Butterfield, Williams L, Adomah, Atkinson
N FOREST : Darlow, Jara, Lascelles, Collins(C), Fox, Greening, Mackie, Paterson (Reid 70), Majewski, Abdoun (Henderson 78), Cox (Derbyshire 78). Subs: De Vries, Harding, Gomis, Moussi.
Ref: Roger East (Wiltshire)
Att: 14,134 (892 visitors)