CVE-2026-94056Network attack vectorHinoki check available

Stack-memory disclosure via incomplete Proxy Protocol header

Published Sep 19, 2026 · Updated Sep 19, 2026

Information disclosure in Exim 4.83 through 4.100 allows remote attackers to read stack data through Proxy Protocol v2. Its Proxy Protocol v2 parser uses an incomplete header's uninitialized length field instead of repeating reads until the full header arrives. Exposure requires Proxy Protocol support, a hosts_proxy configuration, and a buggy or compromised configured proxy; leaked process memory is transmitted remotely.

CVSS severity7.5
High
EPSS probability0.24%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Information disclosure in Exim 4.83 through 4.100 allows remote attackers to read stack data through Proxy Protocol v2. Its Proxy Protocol v2 parser uses an incomplete header's uninitialized length field instead of repeating reads until the full header arrives. Exposure requires Proxy Protocol support, a hosts_proxy configuration, and a buggy or compromised configured proxy; leaked process memory is transmitted remotely.

The record

CVE
CVE-2026-94056
Published
Sep 19, 2026
Updated
Sep 19, 2026
Vendor
LibSPF2 Project
Product
Exim
Classifications
CWE-908, 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=4.83 <4.100.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

LibSPF2 Project · Eximversion=4.83 <4.100.1

Published CVSS scores

7.5MITRE CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:L

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-908Use of Uninitialized Resource
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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