> Source: [sk183067](https://support.checkpoint.com/results/sk/sk183067)

# sk183067 - VPN peer drops ESP packets with message "Warning: possible replay attack"

| Property | Value |
|----------|-------|
| Solution ID | sk183067 |
| Date Created | 2025-02-03 |
| Last Modified | 2025-02-11 |
| Technical Level | General |
| Products | Spark Firewall (Locally Managed) |
| Versions | R81.10.X |

## Symptoms

- * VPN peer drops ESP packets with message "*Warning: possible replay attack*."

* If VPN Accel is disabled, there are no "Replay Attack" logs seen.

* Multiple ESP packets enter the same VPN tunnel and are encrypted with with the same sequence number.

* Example of traffic capture:

  ```
  
  [Expert Info (Warning/Sequence): Wrong Sequence Number for SPI bfd393e4 - 1 repeated]
  [Wrong Sequence Number for SPI bfd393e4 - 1 repeated]
  [Severity level: Warning]
  [Group: Sequence]
  [Previous Frame: 35181]
  ```

## Cause

Multiple ESP packets that enter the same VPN tunnel are encrypted with the same sequence number. As a result, the peer side of the VPN connection drops the packet and treats the traffic as a replay attack.

## Solution

This problem was fixed. The fix is included starting from:

* [R81.10.15](sk182438)

Check Point recommends to always upgrade to the [Recommended version](https://support.checkpoint.com/results/sk/sk179615).

If you choose not to upgrade, [contact Check Point Support](https://www.checkpoint.com/support-services/contact-support/) to get a Hotfix for your version.

A Support Engineer will make sure the Hotfix is compatible with your environment before providing it.  
For faster resolution and verification, collect these files:

1. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Management Server involved in the case.
2. [CPinfo](https://support.checkpoint.com/results/sk/sk92739) file from the Security Gateway / each Cluster Member involved in the case.

**Hotfix installation instructions:**   
Refer to [sk168597 - How to install a Hotfix](https://support.checkpoint.com/results/sk/sk168597).

---

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