CVE-2026-94056: High severity Exim Exim vulnerability

Q: Which deployments are exposed?

Exim deployments using Proxy-Protocol with an attacker-controlled proxy are exposed. The issue affects Exim versions before 4.100.1.

Q: What does an attacker need to exploit this?

The attacker needs network access and an attacker-controlled proxy participating in Proxy-Protocol handling. No privileges or user interaction are required, although exploitation has high attack complexity.

Q: What is the impact?

An attacker may read certain uninitialized data from Exim stack memory. The listed impact includes high confidentiality impact and low availability impact, with no integrity impact.

Published Sep 19, 2026

Updated

Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, allows attackers to read certain uninitialized data from stack memory.

Affected Software

1 affected component

Exim Exim<4.100.1

Event History

Sep 19, 2026

CVE Published

via MITRE·10:52 PM

Data Sourced

via MITRE·10:52 PM

DescriptionSeverityWeakness

Frequently Asked Questions

Which deployments are exposed?

Exim deployments using Proxy-Protocol with an attacker-controlled proxy are exposed. The issue affects Exim versions before 4.100.1.

What does an attacker need to exploit this?

The attacker needs network access and an attacker-controlled proxy participating in Proxy-Protocol handling. No privileges or user interaction are required, although exploitation has high attack complexity.

What is the impact?