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Exim4: Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, has an out-of-bounds write. (CVE-2026-94054)

0
Medium
VulnerabilityCVE-2026-94054gcveosvubuntu-cve-2026-94054cve-2026-94054ubuntu-pro-14-04-ltsubuntu-pro-16-04-ltsubuntu-pro-18-04-ltsubuntu-pro-20-04-ltsubuntu-22-04-ltsubuntu-24-04-ltsubuntu-26-04-lts
Published: 09/19/2026 (09/19/2026, 23:17:00 UTC)
Source: GCVE Database
Product: exim4

Description

Exim versions before 4.100.1 have an out-of-bounds write vulnerability when the Proxy-Protocol feature is used with an attacker-controlled proxy. This flaw can lead to a partial loss of confidentiality, a high impact on integrity, and a low impact on availability. The vulnerability affects many specific Ubuntu package versions of Exim4. The CVSS score is 7.0, indicating a medium severity level.

CVSS v3.1

Score 7.0high

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L

Affected software

Ubuntu:Pro:14.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=esm-infra-legacy/trusty
Affected versions
=4.80-7ubuntu3=4.80-7ubuntu4=4.80-9ubuntu1=4.80-9ubuntu2=4.82-3ubuntu1=4.82-3ubuntu2=4.82-3ubuntu2.1=4.82-3ubuntu2.2=4.82-3ubuntu2.3=4.82-3ubuntu2.4=4.82-3ubuntu2.4+esm1=4.82-3ubuntu2.4+esm2=4.82-3ubuntu2.4+esm3=4.82-3ubuntu2.4+esm4=4.82-3ubuntu2.4+esm6=4.82-3ubuntu2.4+esm7=4.82-3ubuntu2.4+esm8=4.82-3ubuntu2.4+esm9
Ubuntu:Pro:16.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=esm-infra-legacy/xenial
Affected versions
=4.86-3ubuntu1=4.86-7ubuntu1=4.86-7ubuntu2=4.86-7ubuntu3=4.86.2-2ubuntu1=4.86.2-2ubuntu2=4.86.2-2ubuntu2.1=4.86.2-2ubuntu2.2=4.86.2-2ubuntu2.3=4.86.2-2ubuntu2.4=4.86.2-2ubuntu2.5=4.86.2-2ubuntu2.6=4.86.2-2ubuntu2.6+esm1=4.86.2-2ubuntu2.6+esm2=4.86.2-2ubuntu2.6+esm4=4.86.2-2ubuntu2.6+esm5=4.86.2-2ubuntu2.6+esm6=4.86.2-2ubuntu2.6+esm7=4.86.2-2ubuntu2.6+esm8=4.86.2-2ubuntu2.6+esm9
Ubuntu:Pro:18.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=esm-infra/bionic
Affected versions
=4.89-5ubuntu1=4.89-9ubuntu1=4.89-9ubuntu2=4.89-9ubuntu3=4.89-9ubuntu4=4.90.1-1ubuntu1=4.90.1-1ubuntu1.1=4.90.1-1ubuntu1.2=4.90.1-1ubuntu1.3=4.90.1-1ubuntu1.4=4.90.1-1ubuntu1.5=4.90.1-1ubuntu1.8=4.90.1-1ubuntu1.9=4.90.1-1ubuntu1.10=4.90.1-1ubuntu1.10+esm1=4.90.1-1ubuntu1.10+esm2=4.90.1-1ubuntu1.10+esm3=4.90.1-1ubuntu1.10+esm4=4.90.1-1ubuntu1.10+esm5=4.90.1-1ubuntu1.10+esm6
Ubuntu:Pro:20.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=esm-infra/focal
Affected versions
=4.92.1-1ubuntu3=4.92.1-1ubuntu4=4.93~RC2-1ubuntu1=4.93-9ubuntu1=4.93-11ubuntu1=4.93-12ubuntu1=4.93-13ubuntu1=4.93-13ubuntu1.1=4.93-13ubuntu1.5=4.93-13ubuntu1.6=4.93-13ubuntu1.7=4.93-13ubuntu1.8=4.93-13ubuntu1.9=4.93-13ubuntu1.10=4.93-13ubuntu1.11=4.93-13ubuntu1.12=4.93-13ubuntu1.12+esm1
Ubuntu:22.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=jammy
Affected versions
=4.94.2-7ubuntu2=4.95-2ubuntu2=4.95-4ubuntu1=4.95-4ubuntu2=4.95-4ubuntu2.1=4.95-4ubuntu2.2=4.95-4ubuntu2.3=4.95-4ubuntu2.4=4.95-4ubuntu2.5=4.95-4ubuntu2.6=4.95-4ubuntu2.7=4.95-4ubuntu2.8=4.95-4ubuntu2.9=4.95-4ubuntu2.10=4.95-4ubuntu2.11
Ubuntu:24.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=noble
Affected versions
=4.96-17ubuntu2=4.96-17ubuntu2.1=4.97-3ubuntu1=4.97-4ubuntu1=4.97-4ubuntu3=4.97-4ubuntu4=4.97-4ubuntu4.1=4.97-4ubuntu4.2=4.97-4ubuntu4.3=4.97-4ubuntu4.4=4.97-4ubuntu4.5=4.97-4ubuntu4.6=4.97-4ubuntu4.7
Ubuntu:26.04:LTSmore threats →ghsa
exim4
pkg:deb/ubuntu/exim4?arch=source&distro=resolute
Affected versions
=4.98.2-1ubuntu2=4.99-4ubuntu1=4.99.1-1ubuntu1=4.99.1-1ubuntu1.1=4.99.1-1ubuntu1.2=4.99.1-1ubuntu1.3=4.99.1-1ubuntu1.4

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 09/24/2026, 06:21:45 UTC

Technical Analysis

Exim before version 4.100.1 contains an out-of-bounds write vulnerability triggered when the Proxy-Protocol is used with a proxy controlled by an attacker. This vulnerability allows an attacker to cause memory corruption, potentially impacting the integrity of the system and partially compromising confidentiality. The issue is specific to the Proxy-Protocol feature and affects numerous Ubuntu-specific Exim4 package versions as listed. The CVSS 3.1 base score is 7.0 with vector AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:L.

Potential Impact

The vulnerability can lead to an out-of-bounds write, which may allow an attacker to alter memory contents, causing a high impact on data integrity. Confidentiality impact is low, and availability impact is low. There are no known exploits in the wild at this time.

Mitigation Recommendations

A fix is available in Exim version 4.100.1. Users should upgrade to version 4.100.1 or later to remediate this vulnerability. Since this is not a cloud service, manual patching is required. Check the vendor advisory for the latest remediation guidance.

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Technical Details

Gcve Source
db.gcve.eu
Osv Id
UBUNTU-CVE-2026-94054
Osv Schema Version
1.7.0
Ecosystems
["Ubuntu:Pro:14.04:LTS","Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:22.04:LTS","Ubuntu:24.04:LTS","Ubuntu:26.04:LTS"]
Cvss Version
3.1

Threat ID: 6ab4be27f7a7c54106eee995

Added to database: 09/24/2026, 06:07:35 UTC

Last enriched: 09/24/2026, 06:21:45 UTC

Last updated: 09/25/2026, 01:47:46 UTC

Views: 4

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