A plucky woman fought back against a subway perv who slashed and pepper-sprayed her aboard a Brooklyn train early Friday — likely jabbing the creep with his own blade, police sources told The Post.

The 42-year-old woman was snoozing on a southbound R train around 2 a.m. — and woke up at the 36th Street stop in Sunset Park to find Reggie Frank masturbating in front of her, according to sources.

When the woman screamed, Frank, 47 — who has a lengthy rap sheet — pulled out an aerosol can and pepper-sprayed her in the face, the sources said.

Then he displayed a folding knife and slashed the victim’s left hand, cops said.

The woman tried to wrestle the knife from Frank, and it “looks like [she]” turned it on her attacker, police sources said.

Frank was transported to NYU Langone Hospital-Brooklyn for a puncture wound to his left arm and torso. The woman, whom cops described as conscious and alert, was taken to the same hospital.

Frank, of Newark, NJ, was charged with assault, criminal possession of a weapon and public lewdness, cops said.

He has 26 prior arrests, including 11 for public lewdness — and is on probation for one of them, police sources said. Cops were hunting him for yet another public-lewdness case in transit at the time of Friday’s attack, according to the sources.

On Aug. 15, 2015, Frank exposed and “manipulated himself” aboard a train at Union Square, cops said. On Sept. 6, Frank allegedly pulled the same stunt on an uptown No. 3 train at Flatbush Avenue and Grand Army Plaza in Brooklyn.

That incident went viral when victim Tiffany Jackson posted an Instagram photo of the perv — alleging that the train conductor seemed unfazed by the whole incident.

“When I ran to the other conductor and told him what happened, he rolled his eyes, annoyed, and radioed dispatch,” Jackson wrote. “At this point, jerk off guy got off the train and smiled at me as he walked out the station. The conductor grumbled and told me to just go upstairs and report the incident to the booth. I wasn’t even half a step away before the conductor peeled off.”

Frank has also been busted for two misdemeanor assault and menacing incidents, the sources said.