VDB-360395 · CVE-2026-40686 · Nessus 312296

Exim up to 4.99.1 UTF8 out-of-bounds

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.
5.1	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Exim up to 4.99.1. It has been rated as problematic. This affects an unknown part of the component UTF8 Handler. The manipulation leads to out-of-bounds. This vulnerability is referenced as CVE-2026-40686. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Exim up to 4.99.1. It has been rated as problematic. This issue affects an unknown function of the component UTF8 Handler. The manipulation with an unknown input leads to a out-of-bounds vulnerability. Using CWE to declare the problem leads to CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality.

It is possible to read the advisory at seclists.org. The identification of this vulnerability is CVE-2026-40686. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 312296 (Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : Exim vulnerabilities (USN-8228-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 4.99.2 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (312296). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Type

Mail Server Software

Name

Exim

Version

License

open-source

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

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

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 312296
Nessus Name: Ubuntu 22.04 LTS / 24.04 LTS / 25.10 / 26.04 LTS : Exim vulnerabilities (USN-8228-1)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Exim 4.99.2

Timelineinfo

04/30/2026 Advisory disclosed
04/30/2026 +0 days VulDB entry created
05/06/2026 +6 days VulDB entry last update

Sourcesinfo

Advisory: seclists.org
Status: Confirmed
Confirmation: 🔒

CVE: CVE-2026-40686 (🔒)
GCVE (CVE): GCVE-0-2026-40686
GCVE (VulDB): GCVE-100-360395

Entryinfo

Created: 04/30/2026 23:15
Updated: 05/06/2026 23:42
Changes: 04/30/2026 23:15 (53), 05/06/2026 23:42 (2)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.