Vulnerability DatabaseCVE-2026-40686
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CVE-2026-40686
Published:April 30, 2026
Updated:May 18, 2026
In Exim before 4.99.2, when utf8 operators are enabled, there is an out-of-bounds read if large UTF-8 trailing characters are present (malformed UTF-8 header data). Information might be divulged within an error message produced during handling of an unrelated e-mail message.
Affected Packages
https://github.com/Exim/exim.git (GITHUB):
Affected version(s) >=exim-4_50 <exim-4.99.2
Fix Suggestion:
Update to version exim-4.99.2
Related Resources (5)
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessment
https://exim.org/static/doc/security/CVE-2025-40686.txt
https://www.openwall.com/lists/oss-security/2026/04/30/21
https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc
https://exim.org/static/doc/security/CVE-2026-40686.txt
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CVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
NONE
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
3.7
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Weakness Type (CWE)
Out-of-bounds Read
CWE-125
EPSS
Base Score:
0.07