The phrase "scathing rebuke" means a harsh and strong criticism or condemnation of someone or something. It suggests that the criticism is severe and can be damaging. Full definition
It happened a decade ago when Ai Weiwei emerged as a political tour de force in China by undermining his totalitarian regime with scathing rebukes via social media. (victoria-miro.com)
These media reports and others drew a scathing rebuke from the FBI, which worried the false reports could affect the ongoing investigation. (businessinsider.com)
Wednesday's false arrest reports also drew a scathing rebuke from the FBI, which urged the press «to exercise caution and attempt to verify information through appropriate official channels before reporting.» (businessinsider.com)