Let $k \in \mathbb{N}$. For each $1 \leq i \leq k$, let $a_i,b_i \in \mathbb{Z}$ and let
\begin{align*}
L_i: \mathbb{Z} \to \mathbb{Z}
\end{align*}
be the affine map $n \mapsto a_i n + b_i$. Assume that $a_i \neq 0$ for every $1 \leq i \leq k$ and that the ordered coefficient pairs $(a_i,b_i)$ are pairwise distinct. Define
\begin{align*}
F: \mathbb{Z} \to \mathbb{Z}
\end{align*}
by $F(n)=\prod_{i=1}^k L_i(n)$. Assume that the system has no fixed prime divisor, meaning that for every prime $p$ there exists $n \in \mathbb{Z}$ such that $p \nmid F(n)$. For each prime $p$, define
\begin{align*}
\nu(p) := \#\left\{r \in \mathbb{Z}/p\mathbb{Z} : F(r) \equiv 0 \pmod p\right\}.
\end{align*}
For $x \geq 2$, assume that $L_i(n)>1$ for every $n \in \mathbb{N}$ with $1 \leq n \leq x$ and every $1 \leq i \leq k$. Then there exists a constant $C_k>0$, depending only on $k$, such that
\begin{align*}
\#\left\{n \in \mathbb{N} : 1 \leq n \leq x \text{ and } L_1(n),\dots,L_k(n) \text{ are all prime}\right\}
\leq
C_k \mathfrak{S}(L_1,\dots,L_k)\frac{x}{(\log x)^k},
\end{align*}
where the singular series is
\begin{align*}
\mathfrak{S}(L_1,\dots,L_k)
=
\prod_p
\left(1-\frac{1}{p}\right)^{-k}
\left(1-\frac{\nu(p)}{p}\right).
\end{align*}