1. Vulnerability Description

• Comparing unrelated variables using Contain can cause unintended behavior.

2. Vulnerability Countermeasure

• When using Contain, make sure that it is compatible with each other.

3. Sample Code

• Vulnerable Code

class Test {
    def f2[A <: AnyRef](xs: Seq[A], y: Int)                            = xs contains y
    def f5[CC[X] <: Seq[X], A <: AnyRef, B <: AnyVal](xs: CC[A], y: B) = xs contains y 
}

• Safe Code

class Test {
    def f1[A](xs: Seq[A], y: A)                                        = xs contains y
    def f4[CC[X] <: Seq[X], A](xs: CC[A], y: A)                        = xs contains y
}