Important security update for cPanel/WHM servers running Exim mail service
⚠️ Vulnerability Overview
Multiple security vulnerabilities have been discovered in Exim affecting versions prior to 4.99.2.
- CVE-2026-40684
- CVE-2026-40685
- CVE-2026-40686
- CVE-2026-40687
📌 What is Exim?
Exim is a widely used Mail Transfer Agent (MTA) responsible for handling email delivery on Linux servers. It is the default mail server in cPanel/WHM environments, making it a critical component of hosting infrastructure.
🚨 Why This Matters
These vulnerabilities may allow attackers to exploit mail services and potentially:
- Execute unauthorized actions
- Disrupt email services (DoS)
- Bypass security controls
- Abuse your server for spam or malicious activity
✅ Official Fix Released
cPanel has released a patched version Exim 4.99.2 that resolves all affected CVEs.
This fix is included in the following cPanel & WHM versions:
- 136.0.7
- 134.0.23
- 118.0.64
- 110.0.112
🔧 How to Fix
To secure your server, update your cPanel/WHM installation:
Restart Exim service after update:
Verify installed version:
Expected: Exim 4.99.2 or later
📄 cPanel Change Log
Fixed CPANEL-53011: Updated Exim to 4.99.2 addressing all listed vulnerabilities.
View cPanel & WHM Change Log