CVE-2026-40686

MediumCVSS 5.3/10Last modified Nov 11, 2026

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.

Metrics

CVSS 3.1 5.3/10CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Weakness enumeration

CWE-125

Affected software

Vendor	Product	Versions
Exim	Exim	< 4.99.2

References

https://code.exim.org/exim/exim/commit/f2570bde16fb4d4a1242ff363a4c4eecf6372efcPatch
https://exim.org/static/doc/security/CVE-2026-40686.txtBroken Link
https://exim.org/static/doc/security/cve-2026-04.1/CVE2026-40686.assessmentVendor Advisory
https://www.openwall.com/lists/oss-security/2026/04/30/21Mailing List, Third Party Advisory

Timeline

Published: Apr 30, 2026
Last modified: Nov 11, 2026
NVD status: Analyzed

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