diff --git a/src/runtime/api.rs b/src/runtime/api.rs
index 3b6eb16dc9a2..e05f3de3b5eb 100644
--- a/src/runtime/api.rs
+++ b/src/runtime/api.rs
@@ -259,6 +259,21 @@ pub(crate) fn with_text_format_source<R>(
         _str_hold.slice()
     };
 
+    // Every parser reached from here records source positions as an `i32`
+    // (`ast::Loc` via `usize2loc` for JSONC/TOML, JSON5's token locs, YAML's
+    // `Pos`), so an input those offsets cannot represent panics inside the
+    // lexer instead of reporting an error. Reject it before parsing.
+    if bytes.len() > i32::MAX as usize {
+        return Err(global.throw_range_error(
+            bytes.len() as i64,
+            bun_jsc::RangeErrorOptions {
+                field_name: b"input.byteLength",
+                max: i64::from(i32::MAX),
+                ..Default::default()
+            },
+        ));
+    }
+
     let mut log = bun_ast::Log::init();
     let source = bun_ast::Source::init_path_string(path, bytes);
 
diff --git a/test/js/bun/json5/json5.test.ts b/test/js/bun/json5/json5.test.ts
index f1ea1ec31e8a..98a4f41b3ebd 100644
--- a/test/js/bun/json5/json5.test.ts
+++ b/test/js/bun/json5/json5.test.ts
@@ -1699,3 +1699,31 @@ describe("stringify memory", () => {
     expect({ stdout, stderr, exitCode }).toEqual({ stdout: "", stderr: "", exitCode: 0 });
   });
 });
+
+// The JSON5 lexer records every source position as an i32, so an input of
+// 2**31 bytes or more used to abort the process with
+// `panic: int cast: TryFromIntError(PosOverflow)` instead of throwing. It is
+// rejected before parsing, so the Uint8Array below is virtual pages that are
+// never read. The runtime accepts a TypedArray here (the binding takes a
+// Blob, Buffer or string); the declared `string` type is narrower.
+test("parse rejects an input of 2**31 bytes or more instead of panicking", () => {
+  let input: Uint8Array;
+  try {
+    input = new Uint8Array(2 ** 31 + 2);
+  } catch {
+    // The 2 GiB reservation itself can fail on a memory-pressured runner;
+    // there is nothing to test then.
+    return;
+  }
+  let err: any;
+  try {
+    JSON5.parse(input as unknown as string);
+  } catch (e) {
+    err = e;
+  }
+  expect(err?.constructor?.name).toBe("RangeError");
+  expect(err?.code).toBe("ERR_OUT_OF_RANGE");
+  expect(err?.message).toBe(
+    'The value of "input.byteLength" is out of range. It must be <= 2147483647. Received 2147483650',
+  );
+});
diff --git a/test/js/bun/yaml/yaml.test.ts b/test/js/bun/yaml/yaml.test.ts
index cbd9ae14c28a..00b41d14814d 100644
--- a/test/js/bun/yaml/yaml.test.ts
+++ b/test/js/bun/yaml/yaml.test.ts
@@ -4743,3 +4743,31 @@ describe("plain scalar whitespace handling", () => {
     expect(() => YAML.parse("g: -")).toThrow(SyntaxError);
   });
 });
+
+// The YAML scanner records every source position as an i32, so an input of
+// 2**31 bytes or more used to abort the process with
+// `panic: int cast: TryFromIntError(PosOverflow)` instead of throwing. It is
+// rejected before parsing, so the Uint8Array below is virtual pages that are
+// never read. The runtime accepts a TypedArray here (the binding takes a
+// Blob, Buffer or string); the declared `string` type is narrower.
+test("parse rejects an input of 2**31 bytes or more instead of panicking", () => {
+  let input: Uint8Array;
+  try {
+    input = new Uint8Array(2 ** 31 + 2);
+  } catch {
+    // The 2 GiB reservation itself can fail on a memory-pressured runner;
+    // there is nothing to test then.
+    return;
+  }
+  let err: any;
+  try {
+    YAML.parse(input as unknown as string);
+  } catch (e) {
+    err = e;
+  }
+  expect(err?.constructor?.name).toBe("RangeError");
+  expect(err?.code).toBe("ERR_OUT_OF_RANGE");
+  expect(err?.message).toBe(
+    'The value of "input.byteLength" is out of range. It must be <= 2147483647. Received 2147483650',
+  );
+});