tests: add CLSAG fuzz tests

diff --git a/contrib/fuzz_testing/fuzz.sh b/contrib/fuzz_testing/fuzz.sh
index 5c88c37..065dcc3 100755
--- a/contrib/fuzz_testing/fuzz.sh
+++ b/contrib/fuzz_testing/fuzz.sh
@@ -10,12 +10,12 @@ fi
 type="$1"
 if test -z "$type"
 then
-  echo "usage: $0 block|transaction|signature|cold-outputs|cold-transaction|load-from-binary|load-from-json|base58|parse-url|http-client|levin|bulletproof"
+  echo "usage: $0 block|transaction|signature|cold-outputs|cold-transaction|load-from-binary|load-from-json|base58|parse-url|http-client|levin|bulletproof|utf8|clsag|clsag_cout|clsag_message|clsag_pubs"
   exit 1
 fi
 case "$type" in
-  block|transaction|signature|cold-outputs|cold-transaction|load-from-binary|load-from-json|base58|parse-url|http-client|levin|bulletproof|utf8) ;;
-  *) echo "usage: $0 block|transaction|signature|cold-outputs|cold-transaction|load-from-binary|load-from-json|base58|parse-url|http-client|levin|bulletproof|utf8"; exit 1 ;;
+  block|transaction|signature|cold-outputs|cold-transaction|load-from-binary|load-from-json|base58|parse-url|http-client|levin|bulletproof|utf8|clsag|clsag_cout|clsag_message|clsag_pubs) ;;
+  *) echo "usage: $0 block|transaction|signature|cold-outputs|cold-transaction|load-from-binary|load-from-json|base58|parse-url|http-client|levin|bulletproof|utf8|clsag|clsag_cout|clsag_message|clsag_pubs"; exit 1 ;;
 esac
 
 if test -d "fuzz-out/$type"
diff --git a/tests/data/fuzz/clsag/clsag0 b/tests/data/fuzz/clsag/clsag0
new file mode 100644
index 0000000..e69de29
diff --git a/tests/data/fuzz/clsag/clsag1 b/tests/data/fuzz/clsag/clsag1
new file mode 100644
index 0000000..36205ee
Binary files /dev/null and b/tests/data/fuzz/clsag/clsag1 differ
diff --git a/tests/data/fuzz/clsag_cout/clsag0 b/tests/data/fuzz/clsag_cout/clsag0
new file mode 100644
index 0000000..e69de29
diff --git a/tests/data/fuzz/clsag_cout/clsag1 b/tests/data/fuzz/clsag_cout/clsag1
new file mode 100644
index 0000000..31cc17d
--- /dev/null
+++ b/tests/data/fuzz/clsag_cout/clsag1
@@ -0,0 +1 @@
+�7���kq>}`�΄j��@#�]d���|
5n
\ No newline at end of file
diff --git a/tests/data/fuzz/clsag_message/clsag0 b/tests/data/fuzz/clsag_message/clsag0
new file mode 100644
index 0000000..e69de29
diff --git a/tests/data/fuzz/clsag_message/clsag1 b/tests/data/fuzz/clsag_message/clsag1
new file mode 100644
index 0000000..9870828
Binary files /dev/null and b/tests/data/fuzz/clsag_message/clsag1 differ
diff --git a/tests/data/fuzz/clsag_pubs/clsag0 b/tests/data/fuzz/clsag_pubs/clsag0
new file mode 100644
index 0000000..e69de29
diff --git a/tests/data/fuzz/clsag_pubs/clsag1 b/tests/data/fuzz/clsag_pubs/clsag1
new file mode 100644
index 0000000..15515fe
Binary files /dev/null and b/tests/data/fuzz/clsag_pubs/clsag1 differ
diff --git a/tests/fuzz/CMakeLists.txt b/tests/fuzz/CMakeLists.txt
index 3b8ae9e..5d14c51 100644
--- a/tests/fuzz/CMakeLists.txt
+++ b/tests/fuzz/CMakeLists.txt
@@ -294,3 +294,51 @@ target_link_libraries(utf8_fuzz_tests
     ${CMAKE_THREAD_LIBS_INIT}
     ${EXTRA_LIBRARIES}
     $ENV{LIB_FUZZING_ENGINE})
+
+monero_add_minimal_executable(clsag_fuzz_tests clsag.cpp clsag_init.h fuzzer.cpp)
+target_link_libraries(clsag_fuzz_tests
+  PRIVATE
+    cryptonote_core
+    serialization
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${EXTRA_LIBRARIES}
+    $ENV{LIB_FUZZING_ENGINE})
+set_property(TARGET clsag_fuzz_tests
+  PROPERTY
+    FOLDER "tests")
+
+monero_add_minimal_executable(clsag_cout_fuzz_tests clsag_cout.cpp clsag_init.h fuzzer.cpp)
+target_link_libraries(clsag_cout_fuzz_tests
+  PRIVATE
+    cryptonote_core
+    serialization
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${EXTRA_LIBRARIES}
+    $ENV{LIB_FUZZING_ENGINE})
+set_property(TARGET clsag_cout_fuzz_tests
+  PROPERTY
+    FOLDER "tests")
+
+monero_add_minimal_executable(clsag_message_fuzz_tests clsag_message.cpp clsag_init.h fuzzer.cpp)
+target_link_libraries(clsag_message_fuzz_tests
+  PRIVATE
+    cryptonote_core
+    serialization
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${EXTRA_LIBRARIES}
+    $ENV{LIB_FUZZING_ENGINE})
+set_property(TARGET clsag_message_fuzz_tests
+  PROPERTY
+    FOLDER "tests")
+
+monero_add_minimal_executable(clsag_pubs_fuzz_tests clsag_pubs.cpp clsag_init.h fuzzer.cpp)
+target_link_libraries(clsag_pubs_fuzz_tests
+  PRIVATE
+    cryptonote_core
+    serialization
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${EXTRA_LIBRARIES}
+    $ENV{LIB_FUZZING_ENGINE})
+set_property(TARGET clsag_pubs_fuzz_tests
+  PROPERTY
+    FOLDER "tests")
diff --git a/tests/fuzz/clsag.cpp b/tests/fuzz/clsag.cpp
new file mode 100644
index 0000000..825b4c2
--- /dev/null
+++ b/tests/fuzz/clsag.cpp
@@ -0,0 +1,52 @@
+// Copyright (c) 2017-2026, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "serialization/binary_utils.h"
+#include "fuzzer.h"
+#include "clsag_init.h"
+
+#include <string>
+
+using namespace rct;
+
+BEGIN_INIT_SIMPLE_FUZZER()
+  clsag_init();
+END_INIT_SIMPLE_FUZZER()
+
+BEGIN_SIMPLE_FUZZER()
+  if (len > 4096)
+    return 0;
+
+  // fuzz deserialization
+  clsag sig;
+  const std::string blob(reinterpret_cast<const char*>(buf), len);
+  if (!serialization::parse_binary(blob, sig))
+    return 0;
+
+  verRctCLSAGSimple(message, sig, pubs, Cout);
+END_SIMPLE_FUZZER()
diff --git a/tests/fuzz/clsag_cout.cpp b/tests/fuzz/clsag_cout.cpp
new file mode 100644
index 0000000..a501456
--- /dev/null
+++ b/tests/fuzz/clsag_cout.cpp
@@ -0,0 +1,50 @@
+// Copyright (c) 2017-2026, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "fuzzer.h"
+#include "clsag_init.h"
+
+#include <cstring>
+
+using namespace rct;
+
+static_assert(sizeof(key) == 32, "rct::key must be 32 bytes");
+
+BEGIN_INIT_SIMPLE_FUZZER()
+  clsag_init();
+END_INIT_SIMPLE_FUZZER()
+
+BEGIN_SIMPLE_FUZZER()
+  if (len < sizeof(key))
+    return 0;
+
+  // fuzz Cout
+  key cout = Cout;
+  std::memcpy(&cout, buf, sizeof(key));
+  verRctCLSAGSimple(message, clsag_s, pubs, cout);
+END_SIMPLE_FUZZER()
diff --git a/tests/fuzz/clsag_init.h b/tests/fuzz/clsag_init.h
new file mode 100644
index 0000000..ab4fd63
--- /dev/null
+++ b/tests/fuzz/clsag_init.h
@@ -0,0 +1,81 @@
+// Copyright (c) 2017-2026, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "cryptonote_basic/cryptonote_basic.h"
+#include "misc_log_ex.h"
+#include "ringct/rctSigs.h"
+
+using namespace crypto;
+using namespace rct;
+
+static key message;
+static ctkeyV pubs;
+static key Cout;
+static clsag clsag_s;
+
+inline static void clsag_init() {
+  message = identity();
+
+  const size_t N = 11;
+  const size_t idx = 5;
+
+  pubs.clear();
+  pubs.reserve(N);
+
+  for (size_t i = 0; i < N; ++i)
+  {
+    key sk;
+    ctkey tmp;
+
+    skpkGen(sk, tmp.dest);
+    skpkGen(sk, tmp.mask);
+
+    pubs.push_back(tmp);
+  }
+
+  // Set P[idx]
+  key p;
+  skpkGen(p, pubs[idx].dest);
+
+  // Set C[idx]
+  key t = skGen();
+  key u = skGen();
+  addKeys2(pubs[idx].mask,t,u,H);
+
+  // Set commitment offset
+  key t2 = skGen();
+  addKeys2(Cout,t2,u,H);
+
+  // Prepare generation inputs
+  ctkey insk;
+  insk.dest = p;
+  insk.mask = t;
+
+  clsag_s = proveRctCLSAGSimple(message, pubs, insk, t2, Cout, idx, hw::get_device("default"));
+  CHECK_AND_ASSERT_THROW_MES(verRctCLSAGSimple(message, clsag_s, pubs, Cout), "Generated CLSAG does not verify");
+}
diff --git a/tests/fuzz/clsag_message.cpp b/tests/fuzz/clsag_message.cpp
new file mode 100644
index 0000000..044140e
--- /dev/null
+++ b/tests/fuzz/clsag_message.cpp
@@ -0,0 +1,51 @@
+// Copyright (c) 2017-2026, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "fuzzer.h"
+#include "clsag_init.h"
+
+#include <cstring>
+
+using namespace crypto;
+using namespace rct;
+
+static_assert(sizeof(key) == 32, "rct::key must be 32 bytes");
+
+BEGIN_INIT_SIMPLE_FUZZER()
+  clsag_init();
+END_INIT_SIMPLE_FUZZER()
+
+BEGIN_SIMPLE_FUZZER()
+  if (len < sizeof(key))
+    return 0;
+
+  // fuzz message
+  key fuzzed_message = message;
+  std::memcpy(&fuzzed_message, buf, sizeof(key));
+  verRctCLSAGSimple(fuzzed_message, clsag_s, pubs, Cout);
+END_SIMPLE_FUZZER()
diff --git a/tests/fuzz/clsag_pubs.cpp b/tests/fuzz/clsag_pubs.cpp
new file mode 100644
index 0000000..385ddc5
--- /dev/null
+++ b/tests/fuzz/clsag_pubs.cpp
@@ -0,0 +1,52 @@
+// Copyright (c) 2017-2026, The Monero Project
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "fuzzer.h"
+#include "clsag_init.h"
+
+#include <cstring>
+
+using namespace rct;
+
+static_assert(sizeof(key) == 32, "rct::key must be 32 bytes");
+
+BEGIN_INIT_SIMPLE_FUZZER()
+  clsag_init();
+END_INIT_SIMPLE_FUZZER()
+
+BEGIN_SIMPLE_FUZZER()
+  if (len < sizeof(key) + 2)
+    return 0;
+
+  ctkeyV fuzzed_pubs = pubs;
+  const size_t index = buf[0] % fuzzed_pubs.size();
+  key& pub = (buf[1] & 1) ? fuzzed_pubs[index].mask : fuzzed_pubs[index].dest;
+  std::memcpy(&pub, buf + 2, sizeof(key));
+
+  verRctCLSAGSimple(message, clsag_s, fuzzed_pubs, Cout);
+END_SIMPLE_FUZZER()