diff --git a/testing/fuzzers/BUILD.gn b/testing/fuzzers/BUILD.gn
index c6fdbb1..0dbbccc 100644
--- a/testing/fuzzers/BUILD.gn
+++ b/testing/fuzzers/BUILD.gn
@@ -41,6 +41,7 @@
     if (pdf_enable_xfa) {
       deps += [
         ":pdf_bidi_fuzzer_src",
+        ":pdf_cfgas_stringformatter_fuzzer_src",
         ":pdf_cfx_barcode_fuzzer_src",
         ":pdf_codec_jpeg_fuzzer_src",
         ":pdf_css_fuzzer_src",
@@ -158,6 +159,16 @@
       ]
     }
 
+    pdfium_fuzzer("pdf_cfgas_stringformatter_fuzzer_src") {
+      sources = [
+        "pdf_cfgas_stringformatter_fuzzer.cc",
+      ]
+      deps = [
+        "../../xfa/fgas",
+        "../../xfa/fxfa/parser",
+      ]
+    }
+
     pdfium_fuzzer("pdf_cfx_barcode_fuzzer_src") {
       sources = [
         "pdf_cfx_barcode_fuzzer.cc",
diff --git a/testing/fuzzers/pdf_cfgas_stringformatter_fuzzer.cc b/testing/fuzzers/pdf_cfgas_stringformatter_fuzzer.cc
new file mode 100644
index 0000000..8c71bcf
--- /dev/null
+++ b/testing/fuzzers/pdf_cfgas_stringformatter_fuzzer.cc
@@ -0,0 +1,46 @@
+// Copyright 2019 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "xfa/fgas/crt/cfgas_stringformatter.h"
+
+#include <stdint.h>
+
+#include "core/fxcrt/fx_memory.h"
+#include "core/fxcrt/fx_string.h"
+#include "third_party/base/ptr_util.h"
+#include "xfa/fxfa/parser/cxfa_localemgr.h"
+
+namespace {
+
+const wchar_t* const kLocales[] = {L"en", L"fr", L"jp", L"cz"};
+const FX_DATETIMETYPE kTypes[] = {FX_DATETIMETYPE_Date, FX_DATETIMETYPE_Time,
+                                  FX_DATETIMETYPE_DateTime,
+                                  FX_DATETIMETYPE_TimeDate};
+
+}  // namespace
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+  if (size < 4)
+    return 0;
+
+  uint8_t locale_selector = data[0] % FX_ArraySize(kLocales);
+  uint8_t type_selector = data[1] % FX_ArraySize(kTypes);
+  data += 2;
+  size -= 2;
+
+  size_t pattern_len = size / 2;
+  size_t value_len = size - pattern_len;
+  WideString pattern =
+      WideString::FromLatin1(ByteStringView(data, pattern_len));
+  WideString value =
+      WideString::FromLatin1(ByteStringView(data + pattern_len, value_len));
+  WideString result;
+  auto mgr =
+      pdfium::MakeUnique<CXFA_LocaleMgr>(nullptr, kLocales[locale_selector]);
+  auto fmt = pdfium::MakeUnique<CFGAS_StringFormatter>(mgr.get(), pattern);
+  fmt->FormatText(value, &result);
+  fmt->FormatNum(value, &result);
+  fmt->FormatDateTime(value, kTypes[type_selector], &result);
+  return 0;
+}