diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index 933e4cd1ad..55c5df4a95 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -37,6 +37,7 @@ from test_framework.psbt import (
     PSBT_IN_WITNESS_UTXO,
     PSBT_OUT_MUSIG2_PARTICIPANT_PUBKEYS,
     PSBT_OUT_TAP_TREE,
+    PSBT_IN_FINAL_SCRIPTWITNESS,
 )
 from test_framework.script import CScript, OP_TRUE, SIGHASH_ALL, SIGHASH_ANYONECANPAY
 from test_framework.script_util import MIN_STANDARD_TX_NONWITNESS_SIZE
@@ -50,6 +51,7 @@ from test_framework.util import (
     assert_raises_rpc_error,
     find_vout_for_address,
     wallet_importprivkey,
+    bitflipper,
 )
 from test_framework.wallet_util import (
     calculate_input_weight,
@@ -369,6 +371,35 @@ class PSBTTest(BitcoinTestFramework):
         changepos = psbtx["changepos"]
         assert_equal(decoded_psbt["tx"]["vout"][changepos]["scriptPubKey"]["type"], expected_type)
 
+    def test_psbt_with_invalid_signature(self):
+        self.log.info("Test descriptorprocesspsbt with invalid signature in signed PSBT")
+
+        def_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        outputs = [{def_wallet.getnewaddress(address_type="bech32m"): 1}]
+        def_wallet.send(outputs)
+        self.generate(self.nodes[0], 6)
+
+        utxos = [utxo for utxo in def_wallet.listunspent() if utxo["desc"].startswith("tr")]
+        psbt = def_wallet.walletcreatefundedpsbt(utxos, [{def_wallet.getnewaddress(): 0.5}])["psbt"]
+        descs = [desc for desc in def_wallet.listdescriptors(True)["descriptors"] if desc["desc"].startswith("tr")]
+
+        # unload wallet so as to not use the wallet RPC in further process PSBT calls
+        def_wallet.unloadwallet()
+
+        desc_psbt = self.nodes[0].descriptorprocesspsbt(psbt=psbt, descriptors=descs, finalize=True)["psbt"]
+        flawed_psbt = PSBT.from_base64(desc_psbt)
+        valid_sig = flawed_psbt.i[0].map.get(PSBT_IN_FINAL_SCRIPTWITNESS)
+        invalid_sig = bitflipper(valid_sig)
+        flawed_psbt.i[0].map[PSBT_IN_FINAL_SCRIPTWITNESS] = invalid_sig
+        flawed_psbt = flawed_psbt.to_base64()
+
+        result = self.nodes[0].descriptorprocesspsbt(psbt=flawed_psbt, descriptors=descs)
+        assert_equal(result["complete"], False)
+        assert_equal("hex" in result, False)
+
+        # load the default wallet back
+        self.nodes[0].loadwallet(self.default_wallet_name)
+
     def run_test(self):
         # Create and fund a raw tx for sending 10 BTC
         psbtx1 = self.nodes[0].walletcreatefundedpsbt([], {self.nodes[2].getnewaddress():10})['psbt']
@@ -1211,6 +1242,7 @@ class PSBTTest(BitcoinTestFramework):
         if not self.options.usecli:
             self.test_sighash_mismatch()
         self.test_sighash_adding()
+        self.test_psbt_with_invalid_signature()
 
 if __name__ == '__main__':
     PSBTTest(__file__).main()
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index bbad6ea771..b4e597ce1d 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -715,3 +715,6 @@ def wallet_importprivkey(wallet_rpc, privkey, timestamp, *, label=""):
     }]
     import_res = wallet_rpc.importdescriptors(req)
     assert_equal(import_res[0]["success"], True)
+
+def bitflipper(input):
+    assert isinstance(input, bytes)
+    return (int.from_bytes(input, 'little') ^ (1 << random.randrange(len(input) * 8))).to_bytes(len(input), 'little')
\ No newline at end of file

git range-diff ac99af4...7e468a6