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CVE-2026-40686

Published: Apr 30, 2026

Modified: May 1, 2026

PUBLISHED

CVSS v3.1

3.7

LOW

Description

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.

Vendor	Product	Versions
Exim	Exim	affected `0 - < 4.99.2`

Weaknesses (CWE)

CVSS v3.1 Details

CVSS v3.1 Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

References

https://www.openwall.com/lists/oss-security/2026/04/30/21

https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessment

https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efc

https://exim.org/static/doc/security/CVE-2026-40686.txt

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