diff --git a/contracts/libraries/SignatureValidator.sol b/contracts/libraries/SignatureValidator.sol
index 2fd345d7..3377c4fb 100644
--- a/contracts/libraries/SignatureValidator.sol
+++ b/contracts/libraries/SignatureValidator.sol
@@ -1,7 +1,12 @@
 // SPDX-License-Identifier: MIT
 pragma solidity 0.8.25;
 
+import { ECDSA } from "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
+
 library SignatureValidator {
+
+    using ECDSA for bytes32;
+
     error IncorrectSignature(address expectedAddress, bytes32 usedHash, bytes signature);
     error ZeroAddress();
     /**
@@ -34,6 +39,6 @@ library SignatureValidator {
         // TODO use EIP712 compatible format instead
         bytes memory prefix = "\x19Ethereum Signed Message:\n32";
         bytes32 prefixedHash = keccak256(abi.encodePacked(prefix, quoteHash));
-        return ecrecover(prefixedHash, v, r, s) == addr;
+        return prefixedHash.recover(v, r, s) == addr;
     }
 }
diff --git a/contracts/test-contracts/ECDSAError.sol b/contracts/test-contracts/ECDSAError.sol
new file mode 100644
index 00000000..2de57872
--- /dev/null
+++ b/contracts/test-contracts/ECDSAError.sol
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: MIT
+pragma solidity 0.8.25;
+
+// solhint-disable comprehensive-interface
+contract ECDSAError {
+    error ECDSAInvalidSignatureS(bytes32 s);
+}
diff --git a/test/signature-validator-ecdsa.test.ts b/test/signature-validator-ecdsa.test.ts
new file mode 100644
index 00000000..751b7178
--- /dev/null
+++ b/test/signature-validator-ecdsa.test.ts
@@ -0,0 +1,124 @@
+import hre, { ethers, upgrades } from "hardhat";
+import { expect } from "chai";
+import { loadFixture } from "@nomicfoundation/hardhat-toolbox/network-helpers";
+import { getTestPegoutQuote, totalValue } from "./utils/quotes";
+import { LP_COLLATERAL } from "./utils/constants";
+import { deployContract } from "../scripts/deployment-utils/utils";
+
+describe("LBC signature malleability defense", () => {
+  async function deployRealLbc() {
+    // Deploy libraries with real SignatureValidator
+    const network = hre.network.name;
+    const quotesDeployment = await deployContract(
+      "contracts/legacy/Quotes.sol:Quotes",
+      network
+    );
+    const btcUtilsDeployment = await deployContract("BtcUtils", network);
+    const realSignatureValidatorDeployment = await deployContract(
+      "SignatureValidator",
+      network
+    );
+    const bridgeMockDeployment = await deployContract("BridgeMock", network);
+
+    // Deploy LBC with real SignatureValidator
+    const LiquidityBridgeContract = await ethers.getContractFactory(
+      "LiquidityBridgeContract",
+      {
+        libraries: {
+          Quotes: quotesDeployment.address,
+          BtcUtils: btcUtilsDeployment.address,
+          SignatureValidator: realSignatureValidatorDeployment.address,
+        },
+      }
+    );
+
+    const lbcProxy = await upgrades.deployProxy(
+      LiquidityBridgeContract,
+      [
+        bridgeMockDeployment.address, // bridgeAddress
+        ethers.parseEther("0.03"), // minimumCollateral
+        ethers.parseEther("0.5"), // minimumPegIn
+        10, // rewardPercentage
+        60, // resignDelayBlocks
+        2300n * 65164000n, // dustThreshold
+        900, // btcBlockTime
+        false, // mainnet
+      ],
+      {
+        unsafeAllow: ["external-library-linking"],
+      }
+    );
+    await lbcProxy.waitForDeployment();
+
+    // Upgrade to V2 with real SignatureValidator
+    const quotesV2Deployment = await deployContract("QuotesV2", network);
+    const LiquidityBridgeContractV2 = await ethers.getContractFactory(
+      "LiquidityBridgeContractV2",
+      {
+        libraries: {
+          QuotesV2: quotesV2Deployment.address,
+          BtcUtils: btcUtilsDeployment.address,
+          SignatureValidator: realSignatureValidatorDeployment.address,
+        },
+      }
+    );
+
+    const lbc = await upgrades.upgradeProxy(
+      lbcProxy,
+      LiquidityBridgeContractV2,
+      {
+        unsafeAllow: ["external-library-linking"],
+      }
+    );
+    await lbc.waitForDeployment();
+
+    const accounts = await ethers.getSigners();
+    const lp = accounts[1];
+    const user = accounts[2];
+
+    // Register one LP with pegout support
+    await lbc.connect(lp).register("LP", "http://lp.local", true, "both", {
+      value: LP_COLLATERAL,
+    });
+
+    return { lbc, lp, user };
+  }
+
+  it("reverts with ECDSAInvalidSignatureS when depositPegout gets high-s signature", async () => {
+    const { lbc, lp, user } = await loadFixture(deployRealLbc);
+
+    const quote = getTestPegoutQuote({
+      lbcAddress: await lbc.getAddress(),
+      liquidityProvider: lp,
+      refundAddress: user.address,
+      value: ethers.parseEther("1"),
+    });
+
+    const quoteHash = await lbc.hashPegoutQuote(quote);
+
+    const lowS = await lp.signMessage(ethers.getBytes(quoteHash));
+    const parsed = ethers.Signature.from(lowS);
+
+    const secp256k1n =
+      0xfffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141n;
+    const s = BigInt(parsed.s);
+    const sPrime = secp256k1n - s;
+    const vPrime = parsed.v === 27 ? 28 : 27;
+    const malleableSig = ethers.hexlify(
+      ethers.concat([
+        ethers.getBytes(parsed.r),
+        ethers.getBytes(ethers.toBeHex(sPrime, 32)),
+        ethers.getBytes(ethers.toBeHex(vPrime, 1)),
+      ])
+    );
+
+    const errorHelper = await ethers.deployContract("ECDSAError");
+    await errorHelper.waitForDeployment();
+
+    await expect(
+      lbc
+        .connect(user)
+        .depositPegout(quote, malleableSig, { value: totalValue(quote) })
+    ).to.be.revertedWithCustomError(errorHelper, "ECDSAInvalidSignatureS");
+  });
+});