SMTP Smuggling in Exim Mail Server

Publication date: 2026-09-19

Last updated on: 2026-09-19

Assigner: MITRE

Description

Exim before 4.100.1 allows SMTP smuggling in which the received message does not match any sent message, and instead depends on crafted data sent after a rejection during DATA processing.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-19

Last Modified

2026-09-19

Generated

2026-09-20

AI Q&A

2026-09-20

EPSS Evaluated

N/A

NVD

CVE-2026-94057

Affected Vendors & Products

Vendor	Product	Version / Range
exim	exim	to 4.100.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-93	The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs.

Attack-Flow Graph

Executive Summary

Exim before version 4.100.1 is vulnerable to SMTP smuggling. This occurs when the received message does not match any sent message due to crafted data sent after a rejection during DATA processing.

Impact Analysis

This vulnerability could allow attackers to manipulate email messages, potentially leading to unauthorized data access, spoofing, or bypassing security measures.

Mitigation Strategies

Upgrade Exim to version 4.100.1 or later to address the SMTP smuggling vulnerability.

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