1:31 PM PT -- 11/4 -- The former 'RHOC' cast member tells TMZ ... Josh has been telling her his life is in danger since he got locked up in 2016. She says guards have threatened to kill him and he's suffered multiple attacks ... 3 at the hands of inmates and at least one by a guard!
Lauri believes the latest -- which was captured on security video at the Orange County jail in Santa Ana -- shows the attacks are premeditated and likely being facilitated by the jail.
Just like Waring's attorney, Joel Garson, told us ... Lauri claims the protective custody unit her son is in only allows one inmate out at a time, and it's up to the guards to enforce that rule to keep everyone safe.
According to Peterson, the guards failed to do so ... and she thinks it was an intentional move to give the attacker a chance to kill Josh.
The troubled son of former 'RHOC' star Lauri Peterson is recovering after getting slashed in his face during an insane jailhouse ambush ... and TMZ has video of the whole incident.
The brutal attack went down at the Orange County jail in Santa Ana when Josh Waring was on his way back to his cell. He never got there because another inmate jumped out wielding razors wrapped in towels.
This surveillance video of the October 9 showdown shows the attacker sneak into position -- hiding under a staircase -- and then Josh, in pajamas and sandals, is suddenly fighting for his life. Fists start flying and Josh defends himself well for a while -- getting in a few head shots -- but he eventually suffered deep gashes to his chest and face.
The brawl -- which moved off-camera, but was still visible in a mirror -- lasted nearly 90 seconds and only stopped when guards rushed in ... commanding both men to get down on the ground.
Josh's attorney, Joel Garson, tells TMZ ... his client was returning to his cell in the protective custody unit of the jail after making a phone call. He says the normal protocol is for all other inmates to be locked in their cells while another inmate is using the phone.
Garson says guards are supposed to confirm over the intercom that the other inmates are locked away. There's no audio on the surveillance video, so Josh's attorney says he can't tell if that protocol was followed -- but he says he wouldn't be surprised if the attacker was allowed to be out of his cell.
Garson is claiming it could be retaliation against Josh for filing a federal lawsuit against Orange County and its Sheriff's Department for violating his civil rights while he's been behind bars.
Another video shows Josh receiving medical treatment after the attack. He's surrounded by deputies as he describes his injuries. He was concerned the razors used against him weren't sterile, and he could've contracted an STD.
We're told he got 20 stitches to his chest and face, which was slashed from his left eye down to his chin.
The Orange County Sheriff's Department tells us it's opened a criminal investigation into the attack.