Exim up to 4.100.0 out-of-bounds write

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.3$0-$5k1.02

Summaryinfo

A vulnerability categorized as very critical has been discovered in Exim up to 4.100.0. This vulnerability affects unknown code. The manipulation results in out-of-bounds write. This vulnerability is reported as CVE-2026-94054. The attack can be launched remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Exim up to 4.100.0. Affected is an unknown functionality. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, has an out-of-bounds write.

The advisory is available at lists.exim.org. This vulnerability is traded as CVE-2026-94054 since 09/20/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. The technical details are unknown and an exploit is not available. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/20/2026).

Upgrading to version 4.100.1 eliminates this vulnerability.

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Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.3

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.0
CNA Vector (MITRE): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Exim 4.100.1

Timelineinfo

09/19/2026 VulDB entry created
09/20/2026 +0 days Advisory disclosed
09/20/2026 +0 days CVE reserved
09/20/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: lists.exim.org
Status: Confirmed

CVE: CVE-2026-94054 (🔒)
GCVE (CVE): GCVE-0-2026-94054
GCVE (VulDB): GCVE-100-407982

Entryinfo

Created: 09/20/2026 01:01
Changes: 09/20/2026 01:01 (62)
Complete: 🔍
Cache ID: 216::103

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