CVE-2026-94057Network attack vectorHinoki check available

Message integrity loss via rejected DATA mishandling

Published Sep 19, 2026 · Updated Sep 19, 2026

SMTP smuggling in Exim 4.100 and earlier allows remote attackers to alter received message content via crafted post-rejection DATA. The SMTP reception path misidentifies the end of a rejected DATA phase and processes attacker-supplied trailing bytes as a different message. Exploitation requires a DATA-phase rejection; normal receive processing still applies to the smuggled message, limiting the result to message-integrity loss.

CVSS severity4.0
Medium
EPSS probability0.20%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

SMTP smuggling in Exim 4.100 and earlier allows remote attackers to alter received message content via crafted post-rejection DATA. The SMTP reception path misidentifies the end of a rejected DATA phase and processes attacker-supplied trailing bytes as a different message. Exploitation requires a DATA-phase rejection; normal receive processing still applies to the smuggled message, limiting the result to message-integrity loss.

The record

CVE
CVE-2026-94057
Published
Sep 19, 2026
Updated
Sep 19, 2026
Vendor
LibSPF2 Project
Product
Exim
Classifications
CWE-93, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <4.100.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LibSPF2 Project · Eximversion=0 <4.100.1

Published CVSS scores

4.0MITRE CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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