Bruce Springsteen dropped by the penultimate episode of "The Late Show With Stephen Colbert" on Wednesday to give the host a proper sendoff ... and used the spotlight to rip Donald Trump and CBS parent company, Paramount Skydance.

Prior to his performance ... The Boss told the audience, "I’m here in support tonight for Stephen, because you're the first guy in America who's lost his show because we got a president who can't take a joke ... and because Larry and David Ellison feel they need to kiss his ass to get what they want ... Stephen, these are small-minded people."

Springsteen's final jab before he sang was ... "They got no idea what the freedoms of this beautiful country are supposed to be about."

A brutal message, for sure, but not a shocking one for the Boss... Springsteen has been an outspoken critic of Trump, and was among the many celebrities who supported and stumped for former VP Kamala Harris.

As you know ... 'The Late Show' is ending over alleged financial reasons ... but there are plenty who think it's actually getting axed over political pressure -- with Trump being a favorite target for Stephen Colbert.

David Letterman is among those who shouted BS on the money reasoning ... calling CBS brass a bunch of "lying weasels!"