diff --git a/extensions/git-read/src/args.ts b/extensions/git-read/src/args.ts
index aca960c4..92a4b053 100644
--- a/extensions/git-read/src/args.ts
+++ b/extensions/git-read/src/args.ts
@@ -31,7 +31,8 @@ export function isSafeRevision(revision: string): boolean {
 const REPO_PATH_PATTERN = /^[^:/\\?#*[\]'"\s][^:/\\?#*[\]'"\s]*$/;
 
 export function isSafeRepoPath(value: string): boolean {
-  if (value.length === 0 || value.length > 512) return false;
+  if (value.length === 0 || value.length > 512 || value.includes("\0"))
+    return false;
   const segments = value.split("/");
   for (const segment of segments) {
     if (segment === "" || segment === "." || segment === "..") return false;
diff --git a/tests/extensions/git-read/args.test.ts b/tests/extensions/git-read/args.test.ts
index 58cbe710..eefae84a 100644
--- a/tests/extensions/git-read/args.test.ts
+++ b/tests/extensions/git-read/args.test.ts
@@ -149,3 +149,14 @@ test("buildLogArgs clamps the limit and validates inputs", () => {
   assert.throws(() => buildLogArgs({ revision: "-n5" }), InvalidRevisionError);
   assert.throws(() => buildLogArgs({ file: "a/../b" }), InvalidPathError);
 });
+
+test("git argv builders reject NUL bytes in repository paths", () => {
+  const path = "src\0secret.ts";
+
+  assert.throws(
+    () => buildShowArgs({ revision: "HEAD", path }),
+    InvalidPathError,
+  );
+  assert.throws(() => buildDiffArgs({ path }), InvalidPathError);
+  assert.throws(() => buildLogArgs({ file: path }), InvalidPathError);
+});