diff --git a/yarn-project/p2p/src/msg_validators/tx_validator/contract_instance_validator.test.ts b/yarn-project/p2p/src/msg_validators/tx_validator/contract_instance_validator.test.ts
new file mode 100644
index 000000000000..e3f01949139a
--- /dev/null
+++ b/yarn-project/p2p/src/msg_validators/tx_validator/contract_instance_validator.test.ts
@@ -0,0 +1,121 @@
+import { PRIVATE_LOG_SIZE_IN_FIELDS } from '@aztec/constants';
+import { padArrayEnd } from '@aztec/foundation/collection';
+import { Fr } from '@aztec/foundation/curves/bn254';
+import { CONTRACT_INSTANCE_PUBLISHED_EVENT_TAG } from '@aztec/protocol-contracts';
+import { AztecAddress } from '@aztec/stdlib/aztec-address';
+import { computeContractAddressFromInstance } from '@aztec/stdlib/contract';
+import { PublicKeys } from '@aztec/stdlib/keys';
+import { PrivateLog } from '@aztec/stdlib/logs';
+import { mockTxForRollup } from '@aztec/stdlib/testing';
+import {
+  TX_ERROR_INCORRECT_CONTRACT_ADDRESS,
+  TX_ERROR_MALFORMED_CONTRACT_INSTANCE_LOG,
+  type Tx,
+} from '@aztec/stdlib/tx';
+
+import { ContractInstanceTxValidator } from './contract_instance_validator.js';
+
+describe('ContractInstanceTxValidator', () => {
+  let validator: ContractInstanceTxValidator;
+
+  beforeEach(() => {
+    validator = new ContractInstanceTxValidator();
+  });
+
+  const expectValid = async (tx: Tx) => {
+    await expect(validator.validateTx(tx)).resolves.toEqual({ result: 'valid' });
+  };
+
+  const expectInvalid = async (tx: Tx, reason: string) => {
+    await expect(validator.validateTx(tx)).resolves.toEqual({ result: 'invalid', reason: [reason] });
+  };
+
+  /**
+   * Builds a PrivateLog encoding a ContractInstancePublishedEvent.
+   * Layout: [tag, address, version, salt, contractClassId, initializationHash, ...publicKeys(8 fields), deployer]
+   */
+  async function buildContractInstanceLog(opts?: { address?: AztecAddress }): Promise<PrivateLog> {
+    const salt = Fr.random();
+    const contractClassId = Fr.random();
+    const initializationHash = Fr.random();
+    const publicKeys = await PublicKeys.random();
+    const deployer = await AztecAddress.random();
+
+    const instance = {
+      version: 1 as const,
+      salt,
+      currentContractClassId: contractClassId,
+      originalContractClassId: contractClassId,
+      initializationHash,
+      publicKeys,
+      deployer,
+    };
+
+    const correctAddress = await computeContractAddressFromInstance(instance);
+    const address = opts?.address ?? correctAddress;
+
+    // Serialize the event into fields matching the format expected by ContractInstancePublishedEvent.fromLog.
+    // fromLog reads from a buffer: [tag(32 bytes) | address(32) | version(32) | salt(32) | classId(32) | initHash(32) | publicKeys(4*64=256 bytes) | deployer(32)]
+    // PublicKeys serializes as 4 Points, each Point is 2 Fr (x, y) = 64 bytes. Total: 8 Fr fields.
+    const publicKeysBuffer = publicKeys.toBuffer();
+    const publicKeysFields: Fr[] = [];
+    for (let i = 0; i < publicKeysBuffer.length; i += 32) {
+      publicKeysFields.push(Fr.fromBuffer(publicKeysBuffer.subarray(i, i + 32)));
+    }
+
+    const emittedFields: Fr[] = [
+      CONTRACT_INSTANCE_PUBLISHED_EVENT_TAG,
+      address.toField(),
+      new Fr(1), // version
+      salt,
+      contractClassId,
+      initializationHash,
+      ...publicKeysFields,
+      deployer.toField(),
+    ];
+    const emittedLength = emittedFields.length;
+
+    const fields = padArrayEnd(emittedFields, Fr.ZERO, PRIVATE_LOG_SIZE_IN_FIELDS);
+    return new PrivateLog(fields as any, emittedLength);
+  }
+
+  function injectPrivateLog(tx: Tx, log: PrivateLog) {
+    // For a rollup-only tx, private logs live in forRollup.end.privateLogs
+    const privateLogs = tx.data.forRollup!.end.privateLogs;
+    const emptyIdx = privateLogs.findIndex(l => l.isEmpty());
+    if (emptyIdx >= 0) {
+      privateLogs[emptyIdx] = log;
+    } else {
+      throw new Error('No empty private log slot available in mock tx');
+    }
+  }
+
+  it('allows transactions with no contract instance logs', async () => {
+    const tx = await mockTxForRollup(1);
+    await expectValid(tx);
+  });
+
+  it('allows transactions with correct contract instance addresses', async () => {
+    const tx = await mockTxForRollup(2);
+    const log = await buildContractInstanceLog();
+    injectPrivateLog(tx, log);
+    await expectValid(tx);
+  });
+
+  it('rejects transactions with incorrect contract instance addresses', async () => {
+    const tx = await mockTxForRollup(3);
+    const wrongAddress = await AztecAddress.random();
+    const log = await buildContractInstanceLog({ address: wrongAddress });
+    injectPrivateLog(tx, log);
+    await expectInvalid(tx, TX_ERROR_INCORRECT_CONTRACT_ADDRESS);
+  });
+
+  it('rejects transactions with malformed contract instance logs', async () => {
+    const tx = await mockTxForRollup(4);
+    // Create a log that has the right tag but garbage data
+    const fields = padArrayEnd([CONTRACT_INSTANCE_PUBLISHED_EVENT_TAG], Fr.ZERO, PRIVATE_LOG_SIZE_IN_FIELDS);
+    const malformedLog = new PrivateLog(fields as any, 1);
+    injectPrivateLog(tx, malformedLog);
+    await expectInvalid(tx, TX_ERROR_MALFORMED_CONTRACT_INSTANCE_LOG);
+  });
+});
diff --git a/yarn-project/p2p/src/msg_validators/tx_validator/contract_instance_validator.ts b/yarn-project/p2p/src/msg_validators/tx_validator/contract_instance_validator.ts
new file mode 100644
index 000000000000..ee8d39825066
--- /dev/null
+++ b/yarn-project/p2p/src/msg_validators/tx_validator/contract_instance_validator.ts
@@ -0,0 +1,56 @@
+import { type Logger, type LoggerBindings, createLogger } from '@aztec/foundation/log';
+import { ContractInstancePublishedEvent } from '@aztec/protocol-contracts/instance-registry';
+import { computeContractAddressFromInstance } from '@aztec/stdlib/contract';
+import {
+  TX_ERROR_INCORRECT_CONTRACT_ADDRESS,
+  TX_ERROR_MALFORMED_CONTRACT_INSTANCE_LOG,
+  type Tx,
+  type TxValidationResult,
+  type TxValidator,
+} from '@aztec/stdlib/tx';
+
+/** Validates that contract instance deployment logs contain correct addresses. */
+export class ContractInstanceTxValidator implements TxValidator<Tx> {
+  #log: Logger;
+
+  constructor(bindings?: LoggerBindings) {
+    this.#log = createLogger('p2p:tx_validator:contract_instance', bindings);
+  }
+
+  async validateTx(tx: Tx): Promise<TxValidationResult> {
+    const reason = await this.#hasCorrectContractInstanceAddresses(tx);
+    return reason ? { result: 'invalid', reason: [reason] } : { result: 'valid' };
+  }
+
+  async #hasCorrectContractInstanceAddresses(tx: Tx): Promise<string | undefined> {
+    const privateLogs = tx.data.getNonEmptyPrivateLogs();
+    for (const log of privateLogs) {
+      if (!ContractInstancePublishedEvent.isContractInstancePublishedEvent(log)) {
+        continue;
+      }
+
+      let event;
+      try {
+        event = ContractInstancePublishedEvent.fromLog(log);
+      } catch (e) {
+        this.#log.warn(`Rejecting tx ${tx.getTxHash()}: failed to parse contract instance event: ${e}`);
+        return TX_ERROR_MALFORMED_CONTRACT_INSTANCE_LOG;
+      }
+
+      try {
+        const instance = event.toContractInstance();
+        const computedAddress = await computeContractAddressFromInstance(instance);
+        if (!computedAddress.equals(instance.address)) {
+          this.#log.warn(
+            `Rejecting tx ${tx.getTxHash()}: contract instance address mismatch. Claimed ${instance.address}, computed ${computedAddress}`,
+          );
+          return TX_ERROR_INCORRECT_CONTRACT_ADDRESS;
+        }
+      } catch (e) {
+        this.#log.warn(`Rejecting tx ${tx.getTxHash()}: failed to compute contract instance address: ${e}`);
+        return TX_ERROR_MALFORMED_CONTRACT_INSTANCE_LOG;
+      }
+    }
+    return undefined;
+  }
+}
diff --git a/yarn-project/p2p/src/msg_validators/tx_validator/factory.test.ts b/yarn-project/p2p/src/msg_validators/tx_validator/factory.test.ts
index 92ede7a4afaa..6dc67ca9294a 100644
--- a/yarn-project/p2p/src/msg_validators/tx_validator/factory.test.ts
+++ b/yarn-project/p2p/src/msg_validators/tx_validator/factory.test.ts
@@ -14,6 +14,7 @@ import { type MockProxy, mock } from 'jest-mock-extended';
 
 import { AggregateTxValidator } from './aggregate_tx_validator.js';
 import { BlockHeaderTxValidator } from './block_header_validator.js';
+import { ContractInstanceTxValidator } from './contract_instance_validator.js';
 import { DataTxValidator } from './data_validator.js';
 import { DoubleSpendTxValidator } from './double_spend_validator.js';
 import {
@@ -73,6 +74,7 @@ describe('Validator factory functions', () => {
         'doubleSpendValidator',
         'gasValidator',
         'dataValidator',
+        'contractInstanceValidator',
       ]);
     });
 
@@ -170,6 +172,7 @@ describe('Validator factory functions', () => {
         MetadataTxValidator.name,
         SizeTxValidator.name,
         DataTxValidator.name,
+        ContractInstanceTxValidator.name,
         TxProofValidator.name,
       ]);
     });
@@ -187,6 +190,7 @@ describe('Validator factory functions', () => {
         MetadataTxValidator.name,
         SizeTxValidator.name,
         DataTxValidator.name,
+        ContractInstanceTxValidator.name,
         TxProofValidator.name,
       ]);
     });
@@ -221,6 +225,7 @@ describe('Validator factory functions', () => {
         BlockHeaderTxValidator.name,
         DoubleSpendTxValidator.name,
         DataTxValidator.name,
+        ContractInstanceTxValidator.name,
         GasTxValidator.name,
         TxProofValidator.name,
       ]);
diff --git a/yarn-project/p2p/src/msg_validators/tx_validator/factory.ts b/yarn-project/p2p/src/msg_validators/tx_validator/factory.ts
index 849f105b46be..4d4df944a34f 100644
--- a/yarn-project/p2p/src/msg_validators/tx_validator/factory.ts
+++ b/yarn-project/p2p/src/msg_validators/tx_validator/factory.ts
@@ -53,6 +53,7 @@ import type { TxMetaData } from '../../mem_pools/tx_pool_v2/tx_metadata.js';
 import { AggregateTxValidator } from './aggregate_tx_validator.js';
 import { ArchiveCache } from './archive_cache.js';
 import { type ArchiveSource, BlockHeaderTxValidator } from './block_header_validator.js';
+import { ContractInstanceTxValidator } from './contract_instance_validator.js';
 import { DataTxValidator } from './data_validator.js';
 import { DoubleSpendTxValidator, type NullifierSource } from './double_spend_validator.js';
 import { GasLimitsValidator, GasTxValidator } from './gas_validator.js';
@@ -167,6 +168,10 @@ export function createFirstStageTxValidationsForGossipedTransactions(
       validator: new DataTxValidator(bindings),
       severity: PeerErrorSeverity.MidToleranceError,
     },
+    contractInstanceValidator: {
+      validator: new ContractInstanceTxValidator(bindings),
+      severity: PeerErrorSeverity.MidToleranceError,
+    },
   };
 }
 
@@ -218,6 +223,7 @@ function createTxValidatorForMinimumTxIntegrityChecks(
     ),
     new SizeTxValidator(bindings),
     new DataTxValidator(bindings),
+    new ContractInstanceTxValidator(bindings),
     new TxProofValidator(verifier, bindings),
   );
 }
@@ -321,6 +327,7 @@ export function createTxValidatorForAcceptingTxsOverRPC(
     new BlockHeaderTxValidator(new ArchiveCache(db), bindings),
     new DoubleSpendTxValidator(new NullifierCache(db), bindings),
     new DataTxValidator(bindings),
+    new ContractInstanceTxValidator(bindings),
   ];
 
   if (!skipFeeEnforcement) {
diff --git a/yarn-project/stdlib/src/tx/validator/error_texts.ts b/yarn-project/stdlib/src/tx/validator/error_texts.ts
index 6a8326f032a8..57599c12d9d4 100644
--- a/yarn-project/stdlib/src/tx/validator/error_texts.ts
+++ b/yarn-project/stdlib/src/tx/validator/error_texts.ts
@@ -41,5 +41,9 @@ export const TX_ERROR_SIZE_ABOVE_LIMIT = 'Transaction size above size limit';
 // Block header
 export const TX_ERROR_BLOCK_HEADER = 'Block header not found';
 
+// Contract instance
+export const TX_ERROR_INCORRECT_CONTRACT_ADDRESS = 'Incorrect contract instance deployment address';
+export const TX_ERROR_MALFORMED_CONTRACT_INSTANCE_LOG = 'Failed to parse contract instance deployment log';
+
 // General
 export const TX_ERROR_DURING_VALIDATION = 'Unexpected error during validation';