ISB ~ 2 Corinthians 11 v26

false brethren:This may refer (1) to those who claimed to be Christians but were not or (2) to Judaizing Christians who opposed Paul’s ministry and tried to impose the ritual and sacrificial laws of the Old Covenant on Gentile converts to Christianity (cf. Acts 15:1-2; Gal 2:4). The latter meaning would link them to the “false apostles” in Corinth (11:13).