How curl was accidentally Turing-complete for nine months

From curl 8.12 through 8.16, config files could slice variable values and include other config files without an explicit depth cap. Together, these features let curl simulate any two-counter Minsky program. Under the usual idealization of unbounded strings and resources, this construction was Turing-complete.

Curl 8.17.0 added a five-level include cap that breaks this reduction.

Nicolas Seriot

Neat.