diff --git a/.Rbuildignore b/.Rbuildignore
index 232504f..388f1c6 100644
--- a/.Rbuildignore
+++ b/.Rbuildignore
@@ -22,3 +22,4 @@
 ^\.jules(/.*)?$
 ^\.trivyignore\.yaml$
 ^trivy\.yaml$
+^\.semgrepignore$
diff --git a/.jules/sentinel.md b/.jules/sentinel.md
index a8207a4..254f505 100644
--- a/.jules/sentinel.md
+++ b/.jules/sentinel.md
@@ -2,3 +2,7 @@
 **Vulnerability:** Unvalidated inputs passed to `if()` statements can cause process crashes (`condition has length > 1`) or unexpected coercion vulnerabilities.
 **Learning:** In R, optional boolean parameters that default to `NULL` should be validated using explicit runtime type validation (e.g., `if (!is.null(flag) && (!is.logical(flag) || length(flag) != 1 || is.na(flag)))`).
 **Prevention:** Always implement explicit runtime type validation for optional boolean parameters.
+## 2024-07-21 - Fix DoS risk in interactive prompts
+**Vulnerability:** Weak regex validation (`^[0-9]+$`) in interactive `readline()` prompts allowed very large numbers which coercing to `NA` when evaluated with `as.integer()`. When passed to an `if` statement, this caused unhandled exception errors (`condition has length > 1` in modern R versions).
+**Learning:** `readline()` input can be manipulated with extremely large numbers resulting in unexpected coercion failures.
+**Prevention:** Strictly bound expected input in `readline()` routines using an exact match regex like `^[12]$` instead of `^[0-9]+$`.
diff --git a/DESCRIPTION b/DESCRIPTION
index f31d3e1..c90753c 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -10,7 +10,7 @@ Description: Automates fixed item parameter linking for test linking under
     the item response theory paradigm using mirt package estimates.
 License: GPL-3 | file LICENSE
 Imports: mirt, methods
-Suggests: testthat (>= 3.0.0)
+Suggests: testthat (>= 3.0.0), mockery
 Encoding: UTF-8
 Config/testthat/edition: 3
 Config/roxygen2/version: 8.0.0
diff --git a/R/aFIPC.R b/R/aFIPC.R
index 6254651..918e19b 100644
--- a/R/aFIPC.R
+++ b/R/aFIPC.R
@@ -141,7 +141,7 @@ autoFIPC <-
       }
       for (attempt in seq_len(3)) {
         n <- readline(prompt = "Is it correct? (1: Yes 2: No) : ")
-        if (grepl("^[0-9]+$", n)) {
+        if (grepl("^[12]$", n)) {
           return(as.integer(n))
         }
       }
@@ -171,7 +171,7 @@ autoFIPC <-
               readline(
                 prompt = "Do you want to use default BILOG-MG priors for oldform Data? (1: Yes 2: No) : "
               )
-            if (grepl("^[0-9]+$", n)) {
+            if (grepl("^[12]$", n)) {
               return(as.integer(n))
             }
           }
@@ -390,7 +390,7 @@ autoFIPC <-
               readline(
                 prompt = "Do you want to use default BILOG-MG priors for newform Data? (1: Yes 2: No) : "
               )
-            if (grepl("^[0-9]+$", n)) {
+            if (grepl("^[12]$", n)) {
               return(as.integer(n))
             }
           }
diff --git a/tests/testthat/test-sentinel-validation.R b/tests/testthat/test-sentinel-validation.R
index 900f0ee..1a9cf7e 100644
--- a/tests/testthat/test-sentinel-validation.R
+++ b/tests/testthat/test-sentinel-validation.R
@@ -35,3 +35,28 @@ test_that("autoFIPC validates boolean flags for newformBILOGprior, oldformBILOGp
     "Security Error: confirmCommonItems must be a single non-NA logical value or NULL"
   )
 })
+
+test_that("autoFIPC properly handles weak regex for interactive readline coercion", {
+  # Mock readline interactively to throw an error
+  # Using `mockery::stub` requires storing the modified function to use it.
+  # So we will mock using `testthat::local_mocked_bindings` for global environment stub.
+
+  # Create a wrapper function in order to allow mocking base R `readline`
+  my_readline <- function(...) readline(...)
+
+  # We test the behavior using a stubbed function explicitly.
+  my_autoFIPC <- aFIPC::autoFIPC
+  mockery::stub(my_autoFIPC, 'readline', mockery::mock('999', '999', '999'))
+  mockery::stub(my_autoFIPC, 'interactive', mockery::mock(TRUE, TRUE, TRUE))
+
+  expect_error(
+    my_autoFIPC(
+      newformXData = data.frame(A=1),
+      oldformYData = data.frame(A=2),
+      newformCommonItemNames = c('A'),
+      oldformCommonItemNames = c('A'),
+      confirmCommonItems = NULL
+    ),
+    "Too many invalid common item confirmation attempts"
+  )
+})